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| privacy:consent [2026/08/19 03:29] – Turn the brainstorm notes into a full page: consent action as the experimental treatment, verifying the choice registered, reading the TCF, GPC/DNT/USP signals, tool table verified 2026-08-19, and a corpus section over 5,859 papers. Authored by Claude karel.kubicek.claude | privacy:consent [2026/09/16 11:20] (current) – Add the boundary with privacy:data_subject_rights to the GPC section: this page sets the signal, that page owns it as an opt-out right. Authored by Claude karel.kubicek.claude |
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| <WRAP important> | <WRAP important> |
| **The finding that should shape your methods section.** Of the **1,120** papers in [[literature:corpus|this corpus]] that ran an automated web crawl, **349 (31.2%)** say what they did about consent notices at all. Of those 349, **313 say they did not interact with the notice** — so **36 papers in the whole 2010–2026 corpus, across seven venues, state that they clicked one.** That is 3.2% of all crawling papers. | **The finding that should shape your methods section.** Of the **1,120** papers in [[literature:corpus|this corpus]] that ran an automated web crawl, **55 (4.9%)** say in their own words what they did about consent notices. **32** of those describe interacting with one; **22** state that they deliberately did not; 1 does both, in different arms.((Every one of the 349 papers the extraction credits with a stated consent action has now been read against its own full text — the 36 claiming an interaction on 2026-08-19, the 313 labelled //no-interaction// on 2026-09-05. **279 of those 313 give no evidence of their own crawl's consent action**: the label is the extractor's default, not the paper's claim. (Most of the 279 do use the word //consent// somewhere — about an IRB form, an OAuth screen, a banner ad — which is exactly how the extractor came to fill the field.) Full verdicts, one line per paper, on [[provenance:privacy:consent|the provenance page]]; see [[#Almost nobody says what they did about consent]].)) A further 8 papers say they perform no page interaction whatsoever without ever mentioning consent, which takes the lenient count to **63 (5.6%)**. |
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| Two consequences. First, the reviewer question "what did you do about the banner?" has no established answer to point at, so **state yours explicitly** — you will be in a minority that does. Second, when you compare your prevalence number against a published one, check what that paper did with the notice before you conclude anything from the difference: two thirds of the time the paper does not say, and the difference may be entirely the treatment. | That is the number to carry away: **for 1,057 of 1,120 crawling papers (94.4%) you cannot tell from the paper which web was measured** — the pre-consent one or the post-consent one. |
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| | Two consequences. First, the reviewer question "what did you do about the banner?" has no established answer to point at, so **state yours explicitly** — you will be in a small minority that does. Second, when you compare your prevalence number against a published one, check what that paper did with the notice before you conclude anything from the difference. Excluding even the 236 papers for which the question genuinely does not arise, **more than nine in ten still say nothing**, and the difference between your number and theirs may be entirely the treatment. |
| </WRAP> | </WRAP> |
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| * **Do Cookie Banners Respect my Choice?** {[matte2020_cookie]}, IEEE S&P 2020 — the paper that turned "is this banner legal?" into something a crawler can decide, by reading what the CMP //stored// rather than what the banner //said//. Read it for the four-violation taxonomy, which almost every later compliance paper reuses. | * **Do Cookie Banners Respect my Choice?** {[matte2020_cookie]}, IEEE S&P 2020 — the paper that turned "is this banner legal?" into something a crawler can decide, by reading what the CMP //stored// rather than what the banner //said//. Read it for the four-violation taxonomy, which almost every later compliance paper reuses. |
| * **Automated Large-Scale Analysis of Cookie Notice Compliance** {[bouhoula2024automated]}, USENIX Security 2024 — the current reference pipeline: find the notice, classify its buttons with a small language model, drive it, and check the cookies against the site's own declarations. Read it for the numbers you will be asked to beat. | * **Automated Large-Scale Analysis of Cookie Notice Compliance** {[bouhoula2024_automated]}, USENIX Security 2024 — the current reference pipeline: find the notice, classify its buttons with a small language model, drive it, and check the cookies against the site's own declarations. Read it for the numbers you will be asked to beat. |
| * **(Un)informed Consent** {[utz2019_informed]}, CCS 2019 and **Dark Patterns after the GDPR** {[nouwens2020_dark]}, CHI 2020 — the two studies that established that banner //design// moves consent rates, so a banner is a manipulation and not a question. Nouwens et al. is outside this corpus's seven venues; it is still the one everybody cites. | * **(Un)informed Consent** {[utz2019_informed]}, CCS 2019 and **Dark Patterns after the GDPR** {[nouwens2020_dark]}, CHI 2020 — the two studies that established that banner //design// moves consent rates, so a banner is a manipulation and not a question. Nouwens et al. is outside this corpus's seven venues; it is still the one everybody cites. |
| * **A Large-Scale Study of Cookie Banner Interaction Tools** {[demir2024_bannertools]}, PETS 2024 — read before you decide to use an off-the-shelf extension, because it measures how often they actually work. | * **A Large-Scale Study of Cookie Banner Interaction Tools** {[demir2024_bannertools]}, PETS 2024 — read before you decide to use an off-the-shelf extension, because it measures how often they actually work. |
| There are six things a crawl can do, and the corpus records which one each paper chose. They are not interchangeable and they are not on a scale — each answers a different question. | There are six things a crawl can do, and the corpus records which one each paper chose. They are not interchangeable and they are not on a scale — each answers a different question. |
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| ^ Action ^ What it measures ^ What it costs you ^ Papers in the corpus that state it ^ | ^ Action ^ What it measures ^ What it costs you ^ Extraction ^ Verified ^ |
| | **no interaction** — load and leave the banner alone | The **pre-consent** web: what a site does before it has any legal basis. This is the right treatment for a violation study, because tracking before consent is the violation | Not what a user experiences. Any "how much tracking is there" number from this treatment is a floor, not a level | **313** | | | **no interaction** — load and leave the banner alone | The **pre-consent** web: what a site does before it has any legal basis. This is the right treatment for a violation study, because tracking before consent is the violation | Not what a user experiences. Any "how much tracking is there" number from this treatment is a floor, not a level | 313 | **22** | |
| | **accept all** | The **upper bound**: everything the site is prepared to do with permission. The right treatment for enumerating vendors, purposes and the full cookie set | Says nothing about compliance, and over-states what a typical user is exposed to | **15** | | | **accept all** | The **upper bound**: everything the site is prepared to do with permission. The right treatment for enumerating vendors, purposes and the full cookie set | Says nothing about compliance, and over-states what a typical user is exposed to | 15 | **11** | |
| | **reject all** | Whether refusal is honoured. Only meaningful when paired with another arm | On its own it is uninterpretable — you cannot tell "respects rejection" from "has no tracking anyway" | **2** | | | **reject all** | Whether refusal is honoured. Only meaningful when paired with another arm | On its own it is uninterpretable — you cannot tell "respects rejection" from "has no tracking anyway" | 2 | **2** | |
| | **accept and reject** (two arms, same sites) | The **difference**, which is the quantity almost every consent result is actually about | Doubles the crawl, and the two arms must be otherwise identical — same vantage, same time window, same profile handling | **14** | | | **accept and reject** (two arms, same sites) | The **difference**, which is the quantity almost every consent result is actually about | Doubles the crawl, and the two arms must be otherwise identical — same vantage, same time window, same profile handling | 14 | **14** | |
| | **CMP-specific choices** — set individual purposes | Purpose-level compliance: did rejecting //advertising// stop advertising cookies? | Only works on CMPs whose interface you can drive; the population becomes "sites using CMPs your tool supports", which is not the web | **2** | | | **CMP-specific choices** — set individual purposes | Purpose-level compliance: did rejecting //advertising// stop advertising cookies? | Only works on CMPs whose interface you can drive; the population becomes "sites using CMPs your tool supports", which is not the web | 2 | **2** | |
| | **dismiss or remove** — close the banner, or delete it from the DOM | Nothing about consent. Useful only to unblock a crawl whose real subject is something else | Removing the banner from the DOM is **not** a consent choice: no consent string is written, and the site may behave as it does pre-consent. Say "we removed the overlay", never "we declined" | **3** | | | **dismiss or remove** — close the banner, or delete it from the DOM | Nothing about consent. Useful only to unblock a crawl whose real subject is something else | Removing the banner from the DOM is **not** a consent choice: no consent string is written, and the site may behave as it does pre-consent. Say "we removed the overlay", never "we declined" | 3 | **0** | |
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| | The //Verified// column comes from reading each of these 349 papers' own full text (see [[#Almost nobody says what they did about consent|below]] and [[provenance:privacy:consent|the provenance page]]). Two patterns in it are worth carrying away even if you never touch this corpus. **The enum is trustworthy exactly where the paper had to describe two arms**, and unreliable where a single ambiguous word in a methods paragraph could be misread. And **//no interaction// is not a finding about the field, it is a finding about the extractor**: 279 of those 313 papers say nothing about what their own crawl did with a notice, and a further **3** turned out to have driven one after all — the notice-driving crawl of CookieEnforcer {[khandelwal2023automated]}, the BannerClick accept/reject arms of Lin et al. {[lin2024_browsing]}, and the three TCF consent modes of Morel et al. {[morel2026_tcf]}. Read a paper before you count it in either direction. |
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| <WRAP important> | <WRAP important> |
| **Two arms or no claim.** If your result is "sites track users who rejected", you need the rejection arm //and// a baseline. If your result is "sites track before consent", you need the no-interaction arm. A single accept-all crawl supports neither. Only **14 papers in this corpus** run both an accept and a reject arm, which is why so many consent findings are hard to compare. | **Two arms or no claim.** If your result is "sites track users who rejected", you need the rejection arm //and// a baseline. If your result is "sites track before consent", you need the no-interaction arm. A single accept-all crawl supports neither. Only **16 papers in this corpus** run both an accept and a reject arm — the 14 the extraction labels ''accept-and-reject'', which the audit confirmed at 14 out of 14, plus two the audit recovered from the //no interaction// pile. It is why so many consent findings are hard to compare. |
| </WRAP> | </WRAP> |
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| <WRAP important> | <WRAP important> |
| Whether the reload can carry the decision at all is a [[Programming:Stateful Stateless|stateful/stateless]] question. A stateless crawl that clears the profile between visits cannot observe post-consent behaviour on a **later** visit, because the consent cookie went with the profile. In this corpus only **115 crawling papers state both a consent action and a statefulness**, and **93 of those are the no-interaction case**. If you interact with banners, statefulness is not an independent choice — say which you used and why. | Whether the reload can carry the decision at all is a [[Programming:Stateful Stateless|stateful/stateless]] question. A stateless crawl that clears the profile between visits cannot observe post-consent behaviour on a **later** visit, because the consent cookie went with the profile. In this corpus only **32 crawling papers state, in their own words, both a consent action and a statefulness** — 20 that interacted and 12 that deliberately did not. (The extraction puts that figure at 115, but 93 of those are //no-interaction// labels the paper never makes; see below.) Of the 32, **18 are stateless**, which is the combination that most often makes the consent arm unobservable. If you interact with banners, statefulness is not an independent choice — say which you used and why. |
| | </WRAP> |
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| | <WRAP important> |
| | **A fifth check, because on many sites the choice does not switch the tag off at all.** Any site running a Google tag (GA4, Google Ads, Tag Manager) can pass the user's consent state to Google rather than simply loading or not loading the tag, and Google requires advertisers serving the EEA to do so in order to keep ad personalisation and measurement.((Google, "Updates to consent mode for traffic in European Economic Area (EEA)", ''support.google.com/tagmanager/answer/13695607'', fetched 2026-08-19: "we are strengthening the enforcement of our EU user consent policy (EU UCP)… you must collect consent for use of personal data from end users based in the EEA and share consent signals with Google". The page does not itself carry the widely-quoted March 2024 enforcement date, so this page does not assert one.)) The consequence for a crawl is concrete: on a consent-mode site a rejection does **not** stop the Google tag from firing — it fires with ''ad_storage'' and ''analytics_storage'' denied and sends cookieless pings instead. A measurement that counts requests, or counts tags loaded, will conclude that rejection did nothing. A measurement that counts cookies set will conclude it worked. **Say which you counted.** |
| </WRAP> | </WRAP> |
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| Most consent banners on European sites are operated by a **Consent Management Platform (CMP)**, and a large share of those implement IAB Europe's **Transparency and Consent Framework (TCF)**, which standardises both the API and the storage format. That standardisation is what makes consent machine-readable at scale, and it is why so many measurement papers are TCF papers. | Most consent banners on European sites are operated by a **Consent Management Platform (CMP)**, and a large share of those implement IAB Europe's **Transparency and Consent Framework (TCF)**, which standardises both the API and the storage format. That standardisation is what makes consent machine-readable at scale, and it is why so many measurement papers are TCF papers. |
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| | This section covers what you need to know about the TCF //to make and verify a consent choice//. The string itself — its segments and bit layout, the seven places it can be found, decoding it reproducibly against a pinned Global Vendor List, Google's separate Additional Consent string, and what a decoded string does and does not prove about a site's behaviour — is on [[Privacy:TCF Consent Strings|Decoding TCF Consent Strings]]. |
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| TCF sites are a **minority, and you must report the denominator as such.** Matte et al. {[matte2020_cookie]} found a TCF banner on **1,426 of 22,949** reachable European sites (**6.2%**) in 2019; Hils et al. {[hils2021_privacy]} tracked adoption longitudinally and detected TCF implementations on the order of thousands of sites in the top 100k. In Android apps the share is comparable: Morel et al. {[morel2026_tcf]} found TCF in **576 of 4,482 apps (12.85%)**. "Consent on the web" and "TCF consent" are not the same population. | TCF sites are a **minority, and you must report the denominator as such.** Matte et al. {[matte2020_cookie]} found a TCF banner on **1,426 of 22,949** reachable European sites (**6.2%**) in 2019; Hils et al. {[hils2021_privacy]} tracked adoption longitudinally and detected TCF implementations on the order of thousands of sites in the top 100k. In Android apps the share is comparable: Morel et al. {[morel2026_tcf]} found TCF in **576 of 4,482 apps (12.85%)**. "Consent on the web" and "TCF consent" are not the same population. |
| } | } |
| </file> | </file> |
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| | Run against four European news sites on 2026-08-19 from a non-EU vantage, before touching the banner, it returns this — the shape you should expect from a site whose banner is up and unanswered: |
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| | <code> |
| | www.spiegel.de => {"success":true,"cmpId":6,"cmpVersion":1,"tcfPolicyVersion":5, |
| | "eventStatus":"cmpuishown","gdprApplies":true, |
| | "purposeConsents":{}, |
| | "purposeLegitimateInterests":{"1":false,"2":false,"3":false,"4":false, |
| | "5":false,"6":false,"7":true,"8":false,"9":true,"10":true}, |
| | "vendorConsentCount":0, |
| | "tcStringPrefix":"CQpMXQAQpMXQAAGABCENCsFgAAAAAALAAAQ4AAAM"} |
| | www.heise.de => {"success":true,"cmpId":6,...,"eventStatus":"cmpuishown","gdprApplies":true, |
| | "purposeConsents":{},"purposeLegitimateInterests":{},"vendorConsentCount":0} |
| | www.repubblica.it=> {"success":true,"cmpId":123,"cmpVersion":387,...,"tcStringPrefix":""} |
| | www.lemonde.fr => {"error":"no callback within timeout"} |
| | </code> |
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| | Four things that output already teaches you. **''gdprApplies'' was ''true'' from a non-EU IP** on all three that answered — the CMP's own scope decision does not always track your vantage point, so measure it rather than assuming it. **''purposeConsents'' is empty and ''vendorConsentCount'' is 0** while the banner is still up: that is the correct pre-consent state and it is what your no-interaction arm should look like. **Spiegel already asserts legitimate interest for purposes 7, 9 and 10 before any click** — legitimate interest is not consent and is not recorded in ''purposeConsents'', so a study that only reads ''purposeConsents'' will under-count what the site is already doing. And **''lemonde.fr'' defines ''%%__tcfapi%%'' but never invokes the callback within four seconds**, which is why the timeout branch exists: without it your crawler hangs, and without recording the timeout you would score the site as having no TCF. |
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| Three things to record every time, because reviewers ask and papers routinely omit them: | Three things to record every time, because reviewers ask and papers routinely omit them: |
| * **''eventStatus''.** ''useractioncomplete'' is the only value that means a choice was recorded. ''cmpuishown'' with a consent already present is exactly Matte et al.'s //consent stored before choice// violation. | * **''eventStatus''.** ''useractioncomplete'' is the only value that means a choice was recorded. ''cmpuishown'' with a consent already present is exactly Matte et al.'s //consent stored before choice// violation. |
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| **Do not decode the TC string yourself.** It is a versioned bit-packed base64 format; use a maintained decoder and pin its version. Two papers in this corpus report writing their own decoding script, and both had to pin a **Global Vendor List** version to interpret the vendor bitfield — the GVL changes weekly, so a decoded vendor set is only meaningful together with the GVL version you decoded it against. The list is served from ''vendor-list.consensu.org/v3/vendor-list.json'' with numbered archives under ''/v3/archives/'', which is what makes a retrospective decode reproducible at all: **fetch and archive the GVL alongside your crawl**, do not resolve vendor IDs months later. | <WRAP important> |
| | **A consent string set on one site used to be readable on another — this mechanism is retired, and the correction matters.** Under TCF v1.x, and under v2.0's optional //global scope//, a CMP could store the string in a shared cookie on the ''consensu.org'' domain — ''euconsent'' and then ''euconsent-v2'' — readable by any other CMP. Matte et al. {[matte2020_cookie]} tested this in 2019: they planted a consent string in the shared cookie and then asked each site's CMP for its state without touching the banner, and **62 sites (4.3%) returned the same consent string** — their CMP had adopted a consent created by a different CMP entirely. IAB Europe **announced the deprecation of global scope, out-of-band consent and the ''euconsent-v2'' cookie on 22 June 2021, and TC strings established with global scope have been invalid since 1 September 2021.**((IAB Tech Lab, //Transparency and Consent String with Global Vendor & CMP List Formats//, section "What happened to Global Scope and Out of Band?" and the version-history rows for July and September 2021. Fetched from the specification repository on 2026-08-26.)) So the cross-site leakage Matte et al. found is a historical finding, not a hazard of a crawl run today. What survives is the same-site version: a consent string persists across page loads within a site, so a stateful crawl still carries your earlier choice forward. Clear consent storage between visits, or crawl statelessly and reload — and say which you did. |
| | </WRAP> |
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| | **The ''getTCData'' command in the probe above is deprecated.** IAB Tech Lab deprecated it in the CMP API specification with TCF v2.2 (May 2023), in favour of registering an ''addEventListener'' callback; the three required commands are now ''ping'', ''addEventListener'' and ''removeEventListener''. In a four-site spot-check on 2026-08-26 all four CMPs that answered at all still returned a TC string for ''getTCData'', although one set the callback's ''success'' flag to ''false'' while doing so. Published crawlers using the command are therefore not broken. But a CMP is within spec to drop it, and the failure mode is a silently growing "no TCF" bucket. New code should use the listener; [[Privacy:TCF Consent Strings|Decoding TCF Consent Strings]] publishes a tested ''addEventListener'' capture snippet and covers the other six channels the string travels in. |
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| | **Do not decode the TC string ad hoc.** It is a versioned bit-packed base64 format; use a maintained decoder and pin its version — and check //which// package you installed, because the reference implementation moved npm scope and left a three-year-old copy behind under the old name. [[Privacy:TCF Consent Strings|Decoding TCF Consent Strings]] has the details, an audited minimal decoder, and the bit layout it reads. Two papers in this corpus report writing their own decoding script, and both had to pin a **Global Vendor List** version to interpret the vendor bitfield — the GVL changes weekly, so a decoded vendor set is only meaningful together with the GVL version you decoded it against. The list is served from ''vendor-list.consensu.org/v3/vendor-list.json'' with numbered archives under ''/v3/archives/'', which is what makes a retrospective decode reproducible at all: **fetch and archive the GVL alongside your crawl**, do not resolve vendor IDs months later. |
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| **The other reason to read the stored string: it lets you check compliance without trusting the interface.** Smith et al. {[smith2024_gdpr]} decoded TC strings across repeated crawls and found recorded-consent violations in **2.2% of domains and 1.3% of crawls** — a much lower rate than the "72% of sites violate something" headlines elsewhere on this page, precisely because it is a narrow, mechanically checkable question ("does the stored string match the choice made?") rather than a broad legal one. When you report a violation rate, say which of those two kinds of question you asked. | **The other reason to read the stored string: it lets you check compliance without trusting the interface.** Smith et al. {[smith2024_gdpr]} decoded TC strings across repeated crawls and found recorded-consent violations in **2.2% of domains and 1.3% of crawls** — a much lower rate than the "72% of sites violate something" headlines elsewhere on this page, precisely because it is a narrow, mechanically checkable question ("does the stored string match the choice made?") rather than a broad legal one. When you report a violation rate, say which of those two kinds of question you asked. |
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| DNT sent a ''DNT: 1'' request header and exposed ''navigator.doNotTrack''. It failed because nothing obliged anyone to honour it: Libert {[libert2018_automated]} found that only **7%** of privacy policies even contained the string "do not track", and of the ones that did, **64.80% explicitly said they did not honour it** against **19.46%** that committed to honouring it. Among 25 third-party data collectors, nine mentioned DNT and **none offered unqualified support**. | DNT sent a ''DNT: 1'' request header and exposed ''navigator.doNotTrack''. It failed because nothing obliged anyone to honour it: Libert {[libert2018_automated]} found that only **7%** of privacy policies even contained the string "do not track", and of the ones that did, **64.80% explicitly said they did not honour it** against **19.46%** that committed to honouring it. Among 25 third-party data collectors, nine mentioned DNT and **none offered unqualified support**. |
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| | **Where this page stops on GPC.** This section is about **setting** the signal from a crawl and reading what the site recorded. [[Privacy:Data subject rights]] owns GPC as an //opt-out right//: which statutes make it binding, the US Privacy and GPP strings that carry the opt-out onward, what the corpus has measured about whether sites honour it, and the access and deletion requests that sit beside it. If your question is "does this site comply", start there; if it is "how do I make my browser say it", stay here. |
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| It is formally dead. The W3C Tracking Protection Working Group concluded its work and republished both specifications as **W3C Working Group Notes on 17 January 2019**, saying in the status section that "there has not been sufficient deployment of these extensions (as defined) to justify further advancement".((''w3.org/TR/tracking-dnt/'', //Tracking Preference Expression (DNT)//, W3C Working Group Note 17 January 2019. Fetched 2026-08-19.)) Browsers have since diverged rather than converged: **Safari** dropped DNT alongside ITP 2.1 in 2019, and **Firefox removed the checkbox in version 135 (4 February 2025)**, whose release notes point users at "Tell websites not to sell or share my data" — which is GPC.((Mozilla, //Firefox 135.0 release notes//: "The 'Do Not Track' checkbox has been removed from preferences. If you wish to ask websites to respect your privacy, you can use the 'Tell websites not to sell or share my data' setting instead. This option is built on top of the Global Privacy Control (GPC)." Fetched 2026-08-19.)) **Chrome still exposes a DNT toggle.** If your crawl runs a default Chrome profile you may be sending ''DNT'' without meaning to; if it runs a current Firefox, the setting you find in the UI is GPC, not DNT. Check what your browser actually sends rather than what you assume. | It is formally dead. The W3C Tracking Protection Working Group concluded its work and republished both specifications as **W3C Working Group Notes on 17 January 2019**, saying in the status section that "there has not been sufficient deployment of these extensions (as defined) to justify further advancement".((''w3.org/TR/tracking-dnt/'', //Tracking Preference Expression (DNT)//, W3C Working Group Note 17 January 2019. Fetched 2026-08-19.)) Browsers have since diverged rather than converged: **Safari** dropped DNT alongside ITP 2.1 in 2019, and **Firefox removed the checkbox in version 135 (4 February 2025)**, whose release notes point users at "Tell websites not to sell or share my data" — which is GPC.((Mozilla, //Firefox 135.0 release notes//: "The 'Do Not Track' checkbox has been removed from preferences. If you wish to ask websites to respect your privacy, you can use the 'Tell websites not to sell or share my data' setting instead. This option is built on top of the Global Privacy Control (GPC)." Fetched 2026-08-19.)) **Chrome still exposes a DNT toggle.** If your crawl runs a default Chrome profile you may be sending ''DNT'' without meaning to; if it runs a current Firefox, the setting you find in the UI is GPC, not DNT. Check what your browser actually sends rather than what you assume. |
| * an optional ''/.well-known/gpc.json'' resource, by which an **origin** declares awareness of and support for GPC. Read the spec's own caveat before you use it as a compliance measure: it "is not intended to convey whether the origin abides by GPC requests from the user agent accessing the resource". | * an optional ''/.well-known/gpc.json'' resource, by which an **origin** declares awareness of and support for GPC. Read the spec's own caveat before you use it as a compliance measure: it "is not intended to convey whether the origin abides by GPC requests from the user agent accessing the resource". |
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| **There is a standard way to turn it on in an automated browser, and you should use it.** §8 of the specification defines two WebDriver extension commands — ''POST /session/{session id}/privacy'' to set the preference and ''GET /session/{session id}/privacy'' to read it back. Driving the preference through WebDriver rather than through a profile pref or an extension means your setup is reproducible and the "did the browser actually send it?" question has an answer. Verify it end to end anyway: log the outgoing ''Sec-GPC'' header on your own endpoint before you crawl anything. | **There is a standard way to turn it on in an automated browser, and you should use it.** §8 of the specification defines two WebDriver extension commands — ''POST /session/{session id}/privacy'' to set the preference and ''GET /session/{session id}/privacy'' to read it back. Driving the preference through WebDriver rather than through a profile pref or an extension means your setup is reproducible and the "did the browser actually send it?" question has an answer. |
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| On the legal side the specification is explicit that its force is jurisdictional: "At least four states have specifically identified GPC as a valid means to exercise legal opt-out rights." Colorado is the sharpest case — the state Attorney General's office states that GPC has been mandatory there since **1 July 2024** and is currently the **only** universal opt-out mechanism the Department recognises. If your paper claims a site is legally obliged to honour GPC, name the state and cite the regulator, not a vendor blog. | <WRAP important> |
| | **Do not enable GPC by injecting the header. It sets one carrier and not the other, and a site that reads the other sees nothing.** Tested on 2026-08-19 with Playwright/Chromium and ''extraHTTPHeaders: { 'Sec-GPC': '1' }'': |
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| | <code> |
| | Sec-GPC on the navigation request = "1" |
| | navigator.globalPrivacyControl = undefined |
| | </code> |
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| | The header goes out; the DOM property does not exist. Any site whose detection reads ''navigator.globalPrivacyControl'' will treat that browser as not signalling, and your compliance rate will be wrong in a direction you cannot see. How the two carriers are split across real sites is exactly the thing this page told you to measure separately, so do not quietly guarantee that only one of them works. **Set the browser's own preference instead.** In Firefox the relevant preferences in ''StaticPrefList.yaml'' are ''privacy.globalprivacycontrol.enabled'', ''privacy.globalprivacycontrol.functionality.enabled'' and ''privacy.globalprivacycontrol.pbmode.enabled'' (the private-browsing one, overridable by the first).((Verified on 2026-08-19 against ''searchfox.org/mozilla-central'', ''modules/libpref/init/StaticPrefList.yaml''.)) Chromium ships no built-in GPC, so a Chrome-based crawl needs an extension or the WebDriver command above — and either way, **assert both carriers on your own endpoint before the crawl**, not just the header. |
| | </WRAP> |
| | |
| | On the legal side the specification is explicit that its force is jurisdictional: "At least four states have specifically identified GPC as a valid means to exercise legal opt-out rights." That is the spec's own conservative wording; the practical number of US states whose comprehensive privacy laws require honouring a universal opt-out mechanism is now roughly a dozen, and it grows every legislative session — **check the current list for your crawl's date rather than reusing one from a paper**. Colorado is the sharpest case — the state Attorney General's office states that GPC has been mandatory there since **1 July 2024** and is currently the **only** universal opt-out mechanism the Department recognises.((Colorado Attorney General, //Universal Opt-Out Mechanisms//, ''coag.gov/opt-out/'': "Beginning July 1, 2024 … Currently, the only UOOM considered valid by The Department is GPC". Fetched 2026-08-19.)) If your paper claims a site is legally obliged to honour GPC, name the state and cite the regulator, not a vendor blog. |
| |
| The published compliance numbers are low and are the ones to cite. Zimmeck et al. {[zimmeck2023_gpc]} found that of the sites implementing a US Privacy String, only **54 of 464 (12%)** actually opted the user out when GPC was sent. Hausladen et al. {[hausladen2025_websites]} re-ran it at scale over time and found **44% (1,411/3,226)** in December 2023, **43% (1,473/3,402)** in February 2024 and **45% (1,620/3,566)** in April 2024 — a different, narrower denominator (sites with //all// implemented privacy strings set to opt-out), which is exactly the kind of denominator difference that makes two GPC papers look contradictory when they are not. Charatan and Birrell {[charatan2024_steps]} found **2,429 of the top 25,000 sites (9.9%)** offering a manual opt-out-of-sale link in November 2022, **814** honouring GPC by November 2023, and **340** for which GPC was the //only// opt-out mechanism offered. | The published compliance numbers are low and are the ones to cite. Zimmeck et al. {[zimmeck2023_gpc]} found that of the sites implementing a US Privacy String, only **54 of 464 (12%)** actually opted the user out when GPC was sent. Hausladen et al. {[hausladen2025_websites]} re-ran it at scale over time and found **44% (1,411/3,226)** in December 2023, **43% (1,473/3,402)** in February 2024 and **45% (1,620/3,566)** in April 2024 — a different, narrower denominator (sites with //all// implemented privacy strings set to opt-out), which is exactly the kind of denominator difference that makes two GPC papers look contradictory when they are not. Charatan and Birrell {[charatan2024_steps]} found **2,429 of the top 25,000 sites (9.9%)** offering a manual opt-out-of-sale link in November 2022, **814** honouring GPC by November 2023, and **340** for which GPC was the //only// opt-out mechanism offered. |
| |
| <WRAP important> | <WRAP important> |
| **Measure the tool on your own sample before you trust it.** Demir et al. {[demir2024_bannertools]} evaluated banner-interaction extensions and found each one interacts with **12 (65%)** of the banners shown to it on average (SD 21%, min 48%, max 95%). A third of banners are missed, and which third is not random — it correlates with language, with CMP, and with how the banner is injected. If a tool is your instrument, its success rate on //your// crawl is a number your paper owes the reader. | **Measure the tool on your own sample before you trust it.** Demir et al. {[demir2024_bannertools]} evaluated five banner-interaction extensions on a hand-checked sample and found each one interacts with **65% of the banners it was shown**, on average — the paper writes it as "on average, with 12 (65%) (SD: 21%; max: 95% min: 48%) of all banners", where the 12 is the mean count on their sample rather than a rate. A third of banners are missed, and which third is not random — it correlates with language, with CMP, and with how the banner is injected. If a tool is your instrument, its success rate on //your// crawl is a number your paper owes the reader. |
| </WRAP> | </WRAP> |
| |
| ^ Tool ^ What it actually does ^ State on 2026-08-19 ^ Use it when ^ | ^ Tool ^ What it actually does ^ State on 2026-08-19 ^ Use it when ^ |
| | **Consent-O-Matic** ([[https://github.com/cavi-au/Consent-O-Matic|cavi-au/Consent-O-Matic]]), from the team behind {[nouwens2020_dark]} | Per-CMP declarative rules. The only widely used tool that can express **purpose-level** choices rather than just accept-or-dismiss | **Alive.** ''rules/'' holds **204** rule files; last commit on ''master'' **2025-11-07**; latest release **v1.1.5**, 2025-06-17 | You need ''cmp-specific-choices'', or a reject that is a real reject. Coverage is bounded by the 204 rules — everything else is untouched | | | **Consent-O-Matic** ([[https://github.com/cavi-au/Consent-O-Matic|cavi-au/Consent-O-Matic]]), from the team behind {[nouwens2020_dark]} | Per-CMP declarative rules. The only widely used tool that can express **purpose-level** choices rather than just accept-or-dismiss | **Alive.** ''rules/'' holds **204** rule files; last commit on ''master'' **2025-11-07**; latest release **v1.1.5**, 2025-06-17 | You need ''cmp-specific-choices'', or a reject that is a real reject. Coverage is bounded by the 204 rules — everything else is untouched | |
| | **autoconsent** ([[https://github.com/duckduckgo/autoconsent|duckduckgo/autoconsent]]) | A library, not an extension: detects the CMP and drives it. Ships **571** auto-generated and **331** hand-authored site rules | **Alive and the most actively maintained of the set.** Release **v16.23.0** on 2026-08-18; ''main'' committed the same day | You are embedding consent handling in your own crawler. It is a library with a stable API, which is what you want. Note the repo says the reference extension build is deliberately not published to stores — the functionality ships inside DuckDuckGo's own browsers | | | **autoconsent** ([[https://github.com/duckduckgo/autoconsent|duckduckgo/autoconsent]]) | A library, not an extension: detects the CMP and drives it. Ships **567** auto-generated and **356** hand-authored site rules (counted on 2026-09-05) | **Alive and the most actively maintained of the set.** Release **v16.37.0** on 2026-09-05 — fourteen releases in the eighteen days since this row first recorded v16.23.0, which is the rate you are committing to if you pin it | You are embedding consent handling in your own crawler. It is a library with a stable API, which is what you want. Note the repo says the reference extension build is deliberately not published to stores — the functionality ships inside DuckDuckGo's own browsers | |
| | **BannerClick** ([[https://github.com/bannerclick/bannerclick|bannerclick/bannerclick]]) {[rasaii2023_thou]} | An **[[Programming:Crawler:OpenWPM|OpenWPM]] custom command**: detect the banner, then accept or reject it, with the detection and the interaction separable | **Alive.** Default branch ''bannerclick_v0.26.0'', last commit **2025-07-01**; a ''_pets25_artifact'' tag accompanies {[rasaii2025_crumbs]} | You are already on OpenWPM and want both arms. This is the lowest-friction path to an accept/reject design | | | **BannerClick** ([[https://github.com/bannerclick/bannerclick|bannerclick/bannerclick]]) {[rasaii2023_thou]} | An **[[Programming:Crawler:OpenWPM|OpenWPM]] custom command**: detect the banner, then accept or reject it, with the detection and the interaction separable | **Alive.** Default branch ''bannerclick_v0.26.0'', last commit **2025-07-01**; a ''_pets25_artifact'' tag accompanies {[rasaii2025_crumbs]} | You are already on OpenWPM and want both arms. This is the lowest-friction path to an accept/reject design | |
| | **Priv-Accept** ([[https://github.com/marty90/priv-accept|marty90/priv-accept]]) | Selenium plus a keyword heuristic. **Accept only** — there is no reject arm | **Stale.** Last commit on ''main'' **2022-04-13**. Not archived, but four years of Selenium and ChromeDriver drift stand between you and it | You want a cheap accept-all arm and are prepared to fix it. Two papers in this corpus still use it | | | **Priv-Accept** ([[https://github.com/marty90/priv-accept|marty90/priv-accept]]) | Selenium plus a keyword heuristic. **Accept only** — there is no reject arm | **Stale.** Last commit on ''main'' **2022-04-13**. Not archived, but four years of Selenium and ChromeDriver drift stand between you and it | You want a cheap accept-all arm and are prepared to fix it. Two papers in this corpus still use it | |
| | **CookieBlock** ([[https://github.com/dibollinger/CookieBlock|dibollinger/CookieBlock]]) {[bollinger2022automating]} | Not a banner tool. It **classifies cookies by purpose and deletes the ones you rejected** — the enforcement half, not the interaction half | **Stale, and a Manifest V2 extension.** Last commit **2023-12-08**; the crawler **2023-06-03**; the published AMO build dates from 2022 | You want purpose labels for observed cookies. See [[Privacy:Cookies|Classifying Cookies]]. Do not assume the shipped extension still loads in a current Chrome | | | **CookieBlock** ([[https://github.com/dibollinger/CookieBlock|dibollinger/CookieBlock]]) {[bollinger2022automating]} | Not a banner tool. It **classifies cookies by purpose and deletes the ones you rejected** — the enforcement half, not the interaction half | **Stale, and a Manifest V2 extension.** Last commit **2023-12-08**; the crawler **2023-06-03**; the published AMO build dates from 2022 | You want purpose labels for observed cookies. See [[Privacy:Cookies|Classifying Cookies]]. Do not assume the shipped extension still loads in a current Chrome | |
| | **"I don't care about cookies"** | **Hides** banners far more often than it answers them. Acquired by Avast | **Original stale** (published build last updated 2023-11). The maintained Manifest V3 successor is the community fork [[https://github.com/OhMyGuus/I-Still-Dont-Care-About-Cookies|OhMyGuus/I-Still-Dont-Care-About-Cookies]], last commit **2026-06-21** | Almost never, in research. Hiding a banner is ''dismiss-or-remove'', not consent — see the warning below | | | **"I don't care about cookies"** | **Hides** banners far more often than it answers them. Acquired by Avast | **Original stale** (the Firefox build on addons.mozilla.org is **v3.5.0**, last updated **2023-12-06**, checked 2026-09-05). The maintained Manifest V3 successor is the community fork [[https://github.com/OhMyGuus/I-Still-Dont-Care-About-Cookies|OhMyGuus/I-Still-Dont-Care-About-Cookies]], last commit **2026-06-21** | Almost never, in research. Hiding a banner is ''dismiss-or-remove'', not consent — see the warning below | |
| | **Ninja Cookie** | Rule-driven banner rejection | **Abandoned.** The project domain is parked, the GitLab repository has been silent since **2022-02**, and the Firefox listing is gone | Never. It appears in {[demir2024_bannertools]}, which is why it is here — do not carry it forward from that paper into a 2026 crawl | | | **Ninja Cookie** | Rule-driven banner rejection | **Abandoned.** The project domain is parked, the GitLab repository has been silent since **2022-02**, and the Firefox listing is gone | Never. It appears in {[demir2024_bannertools]}, which is why it is here — do not carry it forward from that paper into a 2026 crawl | |
| | **Super Agent** | Commercial, closed-source consent automation | Live commercial product | Not as a research instrument: you cannot pin its version or read its rules | | | **Super Agent** | Commercial, closed-source consent automation | Live commercial product | Not as a research instrument: you cannot pin its version or read its rules | |
| </WRAP> | </WRAP> |
| |
| **Which ones the field actually uses.** Counting papers in this corpus that name a tool as ''used'' or ''produced'': Consent-O-Matic **9**, BannerClick **4**, CookieBlock **4**, a custom GPC extension or crawler **4**, autoconsent **3**, Priv-Accept **2**, a TC-string decoder **2**, and one paper each for ConsentChk, CookieEnforcer, GDPR-Consent, "I don't care about cookies", Ninja Cookie, Opt-Out Easy, OptOutCheck, Super Agent and CookieCheck. The long tail is the finding: **almost every consent paper builds its own instrument**, which is the main reason consent results are hard to compare across papers. | **Which ones the field actually uses.** Counting papers in this corpus that name a tool as ''used'' or ''produced'' — 17 distinct names over 39 papers, folded with ''consent_fold.mjs'': Consent-O-Matic **9**, BannerClick **4**, CookieBlock **4**, a custom GPC extension or crawler **4**, autoconsent **3**, EasyList Cookie List **2**, Priv-Accept **2**, a TC-string decoder **2**, and one paper each for ConsentChk, CookieCheck, CookieEnforcer, GDPR-Consent, "I don't care about cookies", Ninja Cookie, Opt-Out Easy, OptOutCheck and Super Agent. The long tail is the finding: **almost every consent paper builds its own instrument**, which is the main reason consent results are hard to compare across papers. |
| |
| ===== Jurisdiction: Your Vantage Point Chooses Your Banner ===== | ===== Jurisdiction: Your Vantage Point Chooses Your Banner ===== |
| The banner you see is chosen by the site from your IP address. Crawl a European site from a US datacentre and you will often get no banner at all, or a different one — and the TCF's own ''gdprApplies'' flag will be ''false''. This makes [[Design:Crawling location|the vantage point]] a co-determinant of every consent result, not an independent choice. | The banner you see is chosen by the site from your IP address. Crawl a European site from a US datacentre and you will often get no banner at all, or a different one — and the TCF's own ''gdprApplies'' flag will be ''false''. This makes [[Design:Crawling location|the vantage point]] a co-determinant of every consent result, not an independent choice. |
| |
| The corpus says the field mostly does not handle this. Of the **349** crawling papers that state a consent action, **68 (19.5%)** state an EU/EEA vantage point, **72 (20.6%)** state a non-EEA vantage only, and **206 (59.0%)** carry a vantage tuple with the location //not stated//. The picture is better among the papers that actually clicked: of the **36** that interacted with a notice, **21 (58.3%)** did so from an EU/EEA vantage — but that still leaves 15 papers that interacted with EU consent banners without saying they were in the EU. | The corpus says the field handles this better than it reports anything else about consent, but the population that reports anything at all is tiny. Of the **55** crawling papers audited as stating a consent action in their own words, **37 (67.3%)** state an EU/EEA vantage point, **7 (12.7%)** state a non-EEA vantage only, and **11 (20.0%)** carry a vantage tuple whose location is //not stated//. The split barely moves between the papers that clicked and the papers that deliberately did not: of the **32** whose interaction is verified, **22 (68.8%)** were in the EU/EEA; of the **22** that state they left the banner alone, **14 (63.6%)** were. Reading these as encouraging would be a mistake — they are conditional on a paper having said anything, which 94.4% of crawling papers did not. |
| |
| Ogut et al. {[ogut2024_dissecting]} is the paper to read on the language side of the same problem: button text is the classifier's input, and //Accept all// is //Aceptar todo// and //Alle akzeptieren// elsewhere. They found a consent notice on **37% (1511)** of successfully loaded sites worldwide. Tang et al. {[tang2025_navigating]} did the regional comparison for violations, finding at least one consent violation on **96.18% (EU)** to **97.72% (US)** of sites, with only **3.82%** enforcing preferences correctly. | Ogut et al. {[ogut2024_dissecting]} is the paper to read on the language side of the same problem: button text is the classifier's input, and //Accept all// is //Aceptar todo// and //Alle akzeptieren// elsewhere. They found a consent notice on **37% (1511)** of successfully loaded sites worldwide. Tang et al. {[tang2025_navigating]} did the regional comparison for violations, finding at least one consent violation on **96.18% (EU)** to **97.72% (US)** of sites, with only **3.82%** enforcing preferences correctly. |
| Population: the **1,120** papers that ran an automated web crawl. | Population: the **1,120** papers that ran an automated web crawl. |
| |
| ^ ''crawlConfig.consentAction'' ^ Papers ^ Share of 1,120 ^ | ^ ''crawlConfig.consentAction'' ^ Papers ^ Share of 1,120 ^ Supported by the paper ^ |
| | no interaction | 313 | 27.9% | | | no interaction | 313 | 27.9% | **22** | |
| | accept all | 15 | 1.3% | | | accept all | 15 | 1.3% | **11** | |
| | accept and reject | 14 | 1.3% | | | accept and reject | 14 | 1.3% | **14** | |
| | dismiss or remove | 3 | 0.3% | | | dismiss or remove | 3 | 0.3% | **0** | |
| | reject all | 2 | 0.2% | | | reject all | 2 | 0.2% | **2** | |
| | CMP-specific choices | 2 | 0.2% | | | CMP-specific choices | 2 | 0.2% | **2** | |
| | //not stated// | 495 | 44.2% | | | //not stated// | 495 | 44.2% | — | |
| | //not applicable// | 236 | 21.1% | | | //not applicable// | 236 | 21.1% | — | |
| | //no crawl configuration extracted// | 40 | 3.6% | | | //no crawl configuration extracted// | 40 | 3.6% | — | |
| | |
| | **None of the six stated rows survives contact with the papers, and the largest survives worst.** All 349 papers in those rows have now been read against their own full text. |
| | |
| | Among the **36** in the five interacting rows, **7 (19.4%) are extraction false positives** — the value fired on push-notification permission prompts, on "banner ads", and three times on IRB participant consent. |
| | |
| | Among the **313** in the ''no-interaction'' row, **279 (89.1%) are not supported by the paper at all**. ''no-interaction'' is not a sentinel — the same field carries ''not-stated'' and ''not-applicable'' — so it is a positive claim that the crawl left the notice alone, and in 279 cases the paper makes no such claim. 72 of them contain no consent vocabulary anywhere in either rendering of their full text; in the rest, the word the extractor could have been reading is an advertising or protocol "banner", an IRB consent form, an OAuth or cryptomining consent prompt, an industry opt-out programme, or the ISOC copyright boilerplate. A further **3 (1.0%) are false negatives**: those papers do drive a consent notice. **22 (7.0%)** say in words that they did not, and **8** say they perform no interaction at all without ever mentioning consent. |
| | |
| | Both audits are hand adjudications with one recorded verdict and reason per paper: ''consent_action_audit.mjs'' for the 36, ''consent_action_noninteraction_audit.mjs'' for the 313. Both fail loudly on an unadjudicated paper, and every phrase quoted in a verdict is machine-checked against the cited paper. The scripts, their unedited output and all 349 verdicts are on [[provenance:privacy:consent|the provenance page]]. |
| |
| The three italic rows are **sentinels, not answers**. ''not-applicable'' is a legitimate value — a crawl of an API, a mobile app store or a set of non-European sites may have no banner to handle — but ''not-stated'' at 44.2% is the finding: nearly half of all crawling papers leave the reader unable to tell which web they measured. | The three italic rows are **sentinels, not answers**. ''not-applicable'' is a legitimate value — a crawl of an API, a mobile app store or a set of non-European sites may have no banner to handle — but ''not-stated'' at 44.2% is the finding: nearly half of all crawling papers leave the reader unable to tell which web they measured. |
| |
| ==== The reporting gap is not closing, but interaction is spreading ==== | ==== Reporting started with the GDPR, from nothing, and is still rare ==== |
| | |
| | ^ Bucket ^ Crawling papers ^ Extraction: state an action ^ Share ^ **Audited: state an action** ^ **Share** ^ Of those, interacted ^ |
| | | 2010–2013 | 102 | 25 | 24.5% | **0** | **0.0%** | 0 | |
| | | 2014–2017 | 167 | 50 | 29.9% | **0** | **0.0%** | 0 | |
| | | 2018–2021 | 308 | 99 | 32.1% | **11** | **3.6%** | 3 | |
| | | 2022–2024 | 345 | 116 | 33.6% | **25** | **7.2%** | 16 | |
| | | 2025–2026* | 198 | 59 | 29.8% | **19** | **9.6%** | 13 | |
| | |
| | //* provisional venue-years — see the caveat at the top of this section.// |
| |
| ^ Bucket ^ Crawling papers ^ State an action ^ Share ^ Actually interacted ^ Share ^ | The two halves of this table tell opposite stories, and the audited half is the one to believe. On the extraction's numbers the field looks as if it has always reported consent handling at roughly a constant 25–34%, with a dip in the newest bucket. **Not one of those four adjacent movements is statistically significant** (Fisher's exact, all //p// > 0.39) — the apparent peak and fall were noise, and an earlier revision of this page described them as a trend. |
| | 2010–2013 | 102 | 25 | 24.5% | 0 | 0.0% | | |
| | 2014–2017 | 167 | 50 | 29.9% | 0 | 0.0% | | |
| | 2018–2021 | 308 | 99 | 32.1% | 6 | 1.9% | | |
| | 2022–2024 | 345 | 116 | 33.6% | 17 | 4.9% | | |
| | 2025–2026* | 198 | 59 | 29.8% | 13 | 6.6% | | |
| |
| //* provisional venue-years.// Two separate trends. **Whether a paper says anything** has moved by about nine points in sixteen years and is flat since 2018 — this is not a solved reporting problem. **Whether a paper interacts** starts at exactly zero before the GDPR and rises steadily afterwards: the treatment arrived with the law, as you would expect, and is now in roughly one crawling paper in fifteen. | On the audited numbers, **no paper before 2018 states a consent action at all**, which is what you would expect: there was mostly no banner to have a policy about. The jump at the GDPR is real (0/167 to 11/308, //p// = 0.0099; pooled 2010–2017 against 2018–2026, //p// = 3.0 × 10⁻⁷). What comes after it is a rise you should not lean on: 3.6% to 7.2% is //p// = 0.058, and 7.2% to 9.6% is //p// = 0.33 in a bucket that is provisional anyway. The honest reading is that **consent reporting went from nonexistent to rare when the law arrived, and has stayed rare** — under one crawling paper in ten, sixteen years in. The test script is ''consent_ni_significance.py''; both series and every //p// are on the provenance page. |
| |
| ==== The consent literature itself ==== | ==== The consent literature itself ==== |
| |
| ^ Venue ^ Papers in S2 ^ Papers in corpus ^ Share of that venue ^ | ^ Venue ^ Papers in S2 ^ Papers in corpus ^ Share of that venue ^ |
| | PETS | 30 | 510 | 5.9% | | | PETS | 30 | 510 | **5.9%** | |
| | USENIX Security | 14 | 1,410 | 1.0% | | | USENIX Security | 14 | 1,410 | 1.0% | |
| | IMC | 7 | 638 | 1.1% | | |
| | TheWebConf | 8 | 843 | 0.9% | | | TheWebConf | 8 | 843 | 0.9% | |
| | | IMC | 7 | 638 | 1.1% | |
| | CCS | 7 | 990 | 0.7% | | | CCS | 7 | 990 | 0.7% | |
| | NDSS | 3 | 701 | 0.4% | | | NDSS | 3 | 701 | 0.4% | |
| | IEEE S&P | 3 | 767 | 0.4% | | | IEEE S&P | 3 | 767 | 0.4% | |
| |
| **PETS is where this work lives**, by a factor of six over the next venue as a share of its own programme. If you are surveying consent measurement and you skip PETS, you have skipped the field. (Note also that this corpus does not contain CHI, SOUPS, EuroS&P, ACSAC or WPES, all of which publish consent work — see the limitations below.) | **PETS is where this work lives**, by more than a factor of five over the next venue as a share of its own programme. If you are surveying consent measurement and you skip PETS, you have skipped the field. (Note also that this corpus does not contain CHI, SOUPS, EuroS&P, ACSAC or WPES, all of which publish consent work — see the limitations below.) |
| |
| Per year: 1 (2018), 4 (2019), 3 (2020), 5 (2021), 9 (2022), 9 (2023), **20 (2024)**, 15 (2025*), 6 (2026*). The pre-2018 count is essentially zero, which is what you would expect of a literature created by a statute. | Per year: 1 (2018), 4 (2019), 3 (2020), 5 (2021), 9 (2022), 9 (2023), **20 (2024)**, 15 (2025*), 6 (2026*). The pre-2018 count is essentially zero, which is what you would expect of a literature created by a statute. |
| |
| In **60 of the 72 (83.3%)** the consent mechanism is the object of study; in the other **12 (16.7%)** it appears only as an instrument — a paper measuring something else that had to get past the banner. **57 (79.2%)** measure the web and **15 (20.8%)** measure mobile apps; consent-dialog measurement in apps is a real and growing subfield {[nguyen2022_freely,koch2023_enough,morel2026_tcf,zimmeck2026_exercising]}, and its methods do not transfer from the web unchanged. | In **60 of the 72 (83.3%)** the consent mechanism is the object of study; in the other **12 (16.7%)** it appears only as an instrument — a paper measuring something else that had to get past the banner. **57** measure the web and **15** measure mobile apps — the field is multi-valued and a paper can do both, and 7 also measure some other online service — so these are not two halves of a partition. Consent-dialog measurement in apps is a real and growing subfield {[nguyen2022_freely,koch2023_enough,morel2026_tcf,zimmeck2026_exercising]}, and its methods do not transfer from the web unchanged. |
| |
| ==== How consent notices get classified ==== | ==== How consent notices get classified ==== |
| | LLM | 1 | 4.2% | | | LLM | 1 | 4.2% | |
| |
| Shares do not sum to 100% because a paper usually stacks several. The shape is the point: **this is still a hand-built-heuristic field.** Supervised ML enters only with CookieEnforcer {[khandelwal2023automated]} and Bouhoula et al. {[bouhoula2024automated]}, both using BERT-class models on button text, and **exactly one paper in the corpus classifies a consent artefact with an LLM** — WhisperTest (CCS 2025), which uses Qwen2.5-7B for iOS UI automation rather than for consent semantics. | Shares do not sum to 100% because a paper usually stacks several. The shape is the point: **this is still a hand-built-heuristic field.** Supervised ML enters only with CookieEnforcer {[khandelwal2023automated]} and Bouhoula et al. {[bouhoula2024_automated]}, both using BERT-class models on button text, and **exactly one paper in the corpus classifies a consent artefact with an LLM** — WhisperTest (CCS 2025), which uses Qwen2.5-7B for iOS UI automation rather than for consent semantics. |
| |
| Validation is better here than on most pages: **19 of 24 (79.2%)** report manual validation and **19 of 24** name a ground-truth source; 4 report no validation at all. Since manual validation of a notice detector is cheap — a few hundred screenshots — there is no excuse for being in the last group. | Validation is better here than on most pages: **19 of 24 (79.2%)** report manual validation and **19 of 24** name a ground-truth source; 4 report no validation at all. Since manual validation of a notice detector is cheap — a few hundred screenshots — there is no excuse for being in the last group. |
| | US children / education / health / finance (COPPA, …) | 7 | 13.2% | | | US children / education / health / finance (COPPA, …) | 7 | 13.2% | |
| | EU platform / digital-market regulation (DSA, …) | 2 | 3.8% | | | EU platform / digital-market regulation (DSA, …) | 2 | 3.8% | |
| | |
| | Three further families carry one paper each and are omitted above: non-EU/US data protection law, a national-rules catch-all, and one string the fold could not place. The unfolded residue is on the provenance page. |
| |
| **The GDPR is not the cookie law.** Consent for storing or reading information on a device comes from Article 5(3) of the **ePrivacy Directive**; the GDPR supplies the definition of valid consent that Article 5(3) points at. Only 20 of 53 papers name ePrivacy at all, and a compliance claim that cites the GDPR alone for a cookie finding is citing the wrong instrument. That also changes **who enforces it** — see [[Practices:Legal enforcement|Legal enforcement]]. | **The GDPR is not the cookie law.** Consent for storing or reading information on a device comes from Article 5(3) of the **ePrivacy Directive**; the GDPR supplies the definition of valid consent that Article 5(3) points at. Only 20 of 53 papers name ePrivacy at all, and a compliance claim that cites the GDPR alone for a cookie finding is citing the wrong instrument. That also changes **who enforces it** — see [[Practices:Legal enforcement|Legal enforcement]]. |
| |
| If you are turning observations into violation claims, two EDPB documents are the cheapest way to align your rules with what regulators actually said, and both are worth reading before you write your own taxonomy: the **Report of the work undertaken by the Cookie Banner Taskforce** (18 January 2023), which is the closest thing to an agreed list of what a non-compliant banner looks like across the EU, and **Opinion 08/2024 on Valid Consent in the Context of Consent or Pay Models Implemented by Large Online Platforms** (17 April 2024), which is the reference for cookiewall studies of the kind Rasaii et al. {[rasaii2023_thou]} pioneered.((Both fetched from ''edpb.europa.eu'' on 2026-08-19; the dates above are the dates the EDPB's own document pages carry. Opinion 08/2024 also has a published corrigendum — check you have the corrected version.)) | If you are turning observations into violation claims, three EDPB documents are the cheapest way to align your rules with what regulators actually said, and all three are worth reading before you write your own taxonomy:((All three fetched from ''edpb.europa.eu'' on 2026-08-19; the dates are the ones the EDPB's own document pages carry. Opinion 08/2024 has a published corrigendum — check you have the corrected version.)) |
| | |
| | * **Report of the work undertaken by the Cookie Banner Taskforce** (18 January 2023) — the closest thing to an agreed list of what a non-compliant banner looks like across the EU. |
| | * **Guidelines 2/2023 on the Technical Scope of Art. 5(3) of the ePrivacy Directive**, final version **16 October 2024** — the one that decides **what your measurement is even allowed to be about**. It reads Article 5(3) as covering far more than cookies: tracking pixels, URL and link decoration, local processing followed by transmission, and IP-only tracking. If your study measures "cookie consent" and your denominator is cookies, this document says you have scoped the legal question too narrowly. |
| | * **Opinion 08/2024 on Valid Consent in the Context of Consent or Pay Models Implemented by Large Online Platforms** (17 April 2024) — the reference for cookiewall studies of the kind Rasaii et al. {[rasaii2023_thou]} pioneered. |
| |
| ==== What the papers found: figures with their own denominators ==== | ==== What the papers found: figures with their own denominators ==== |
| | Sites with **at least one** suspected violation | 54.29% (304) | 560 hand-checked TCF sites | {[matte2020_cookie]} | | | Sites with **at least one** suspected violation | 54.29% (304) | 560 hand-checked TCF sites | {[matte2020_cookie]} | |
| | Sites setting non-necessary cookies **without any interaction** | 69.7% | sites examined | {[bollinger2022automating]} | | | Sites setting non-necessary cookies **without any interaction** | 69.7% | sites examined | {[bollinger2022automating]} | |
| | Sites with at least one cookie-notice violation, 2024 | 72.2% | successfully crawled sites | {[bouhoula2024automated]} | | | Sites with at least one cookie-notice violation, 2024 | 72.2% | successfully crawled sites | {[bouhoula2024_automated]} | |
| | Sites with at least one consent violation, 2025 | 96.18% (EU) – 97.72% (US) | sites per region | {[tang2025_navigating]} | | | Sites with at least one consent violation, 2025 | 96.18% (EU) – 97.72% (US) | sites per region | {[tang2025_navigating]} | |
| | Sites enforcing preferences correctly | 3.82% | same | {[tang2025_navigating]} | | | Sites enforcing preferences correctly | 3.82% | same | {[tang2025_navigating]} | |
| * **Sentinels are counted as what they are.** ''not-stated'' and ''not-applicable'' are never folded into a stated value; where they are the largest row, that is the finding. | * **Sentinels are counted as what they are.** ''not-stated'' and ''not-applicable'' are never folded into a stated value; where they are the largest row, that is the finding. |
| * **Free-text names were folded before counting, and the residue is printed.** The consent-tool fold leaves 5 distinct unmapped names over 5 papers, all of them IAB artefacts that are not banner-interaction tools (''IAB ads.txt crawler'', ''IAB anti-ad-block script'', the IAB content taxonomy). The law fold leaves 2 (''Digital Economy Act 2017'', ''Act against Unfair Competition (UWG)''). The vantage fold leaves 5 strings that name no place (''different continents'', ''various geographic regions''). | * **Free-text names were folded before counting, and the residue is printed.** The consent-tool fold leaves 5 distinct unmapped names over 5 papers, all of them IAB artefacts that are not banner-interaction tools (''IAB ads.txt crawler'', ''IAB anti-ad-block script'', the IAB content taxonomy). The law fold leaves 2 (''Digital Economy Act 2017'', ''Act against Unfair Competition (UWG)''). The vantage fold leaves 5 strings that name no place (''different continents'', ''various geographic regions''). |
| * **Every per-paper figure in the table above was checked against the paper's own text**, not against the extraction's summary of it: 61 literals, 60 found in both the column-repaired and the plain rendering, 1 in the column-repaired rendering only, **0 not found**. That pass caught two errors in an earlier draft of this page — a figure attributed to Bouhoula et al. that the paper writes without a thousands separator, and a Matte et al. percentage this page had rounded to the wrong decimal. | * **Every per-paper figure on this page was checked against the paper's own text**, not against the extraction's summary of it. The check covers 61 literals — a superset of what is published, since ten were checked and then cut — and found 60 in both the column-repaired and the plain rendering, 1 in the column-repaired rendering only, and **0 not found**. That pass caught two errors in an earlier draft of this page — a figure attributed to Bouhoula et al. that the paper writes without a thousands separator, and a Matte et al. percentage this page had rounded to the wrong decimal. |
| * **''consentAction'' is one of the schema's more reliable fields**: an independent extraction run over the same text agrees with it on **93%** of papers, which is why it is published as a percentage rather than a ranking. That figure was measured on the earlier 4,322-paper corpus and has not been re-measured since. | * **''consentAction'' was audited paper by paper, in both directions, and it needed to be.** The schema's stability comparison puts it in the reliable band — an independent extraction run over the same text agrees with it on 93% of papers — but that measures whether two runs agree, not whether either is right, and it was measured on the earlier 4,322-paper corpus. Reading all 36 interacting papers found **7 false positives (19.4%)**, concentrated in ''accept-all'' and ''dismiss-or-remove''. Reading all 313 ''no-interaction'' papers found **279 (89.1%) that make no claim about their own crawl's consent action** and **3 (1.0%) that in fact drove a notice**. The two error modes are different in kind: on the interacting side the extractor misreads a word, on the ''no-interaction'' side it supplies a default where the paper is silent — which is why the second error is twenty times more common and matters more, since it is what inflates every "share of papers that report X" figure. **Note also that the field's own evidence quote cannot catch either**: ''crawlConfig'' carries one quote for the whole configuration object, so the quote behind a ''consentAction'' value usually evidences statefulness or crawl depth instead. Spot-checking quotes, which is the standard check on this site, is structurally blind here. |
| * **Venue coverage.** Seven venues only. **CHI, SOUPS, EuroS&P, ACSAC, RAID, AsiaCCS and WPES are absent**, and that bites harder on this page than on most: the usable-privacy half of the consent literature (Nouwens et al., Habib et al., Utz et al.'s follow-ups) is largely CHI and SOUPS work. Every count here is a lower bound. | * **Venue coverage.** Seven venues only. **CHI, SOUPS, EuroS&P, ACSAC, RAID, AsiaCCS and WPES are absent**, and that bites harder on this page than on most: the usable-privacy half of the consent literature (Nouwens et al., Habib et al., Utz et al.'s follow-ups) is largely CHI and SOUPS work. Every count here is a lower bound. |
| |
| - **Which law you are assessing, by article.** ePrivacy Art. 5(3) for the storage/access question, GDPR Art. 4(11) and 7 for the validity-of-consent question; both, usually. | - **Which law you are assessing, by article.** ePrivacy Art. 5(3) for the storage/access question, GDPR Art. 4(11) and 7 for the validity-of-consent question; both, usually. |
| - **The banner language and the site's locale**, if your button classifier is language-dependent {[ogut2024_dissecting]}. | - **The banner language and the site's locale**, if your button classifier is language-dependent {[ogut2024_dissecting]}. |
| | - **Whether you cleared shared-domain consent cookies between sites**, if the crawl is stateful. A consent string set on one site is readable on another {[matte2020_cookie]}. |
| | - **What you counted as the effect of the choice** — requests, tags loaded, or cookies set. On a Google consent-mode site these disagree, because the tag fires either way. |
| - **Your violation definition, verbatim**, and preferably as machine-checkable rules. This is what makes your 72% and someone else's 96% comparable. | - **Your violation definition, verbatim**, and preferably as machine-checkable rules. This is what makes your 72% and someone else's 96% comparable. |
| |
| ===== Open Questions ===== | ===== Open Questions ===== |
| |
| <wrap todo> | <WRAP todo> |
| * **Nobody has replicated the banner-interaction-tool evaluation since 2024.** Demir et al.'s 65% is one measurement, on one sample, of tools that have since changed. It is load-bearing for a lot of this page and for a lot of published crawls, and re-running it is a well-scoped, publishable study. | * **Nobody has replicated the banner-interaction-tool evaluation since 2024.** Demir et al.'s 65% is one measurement, on one sample, of tools that have since changed. It is load-bearing for a lot of this page and for a lot of published crawls, and re-running it is a well-scoped, publishable study. |
| * **LLM-driven banner interaction is unmeasured as an //instrument//, and alarming as a //subject//.** A language model that reads any banner in any language is the obvious successor to CSS-selector rule sets, and exactly one paper in this corpus puts an LLM anywhere near a consent artefact. Nobody has published cost, latency, determinism or accuracy against a hand-labelled set — and determinism is the hard one for a measurement instrument. Meanwhile the reverse question is opening up: work outside this corpus reports that browser-automation agents accept consent banners even when instructed to refuse everything.((Reported in a CHI 2026 Extended Abstracts paper on browser automation by LLM agents and consent, which measures agents defaulting to accept under explicit deny-all instructions. Not in this corpus (CHI is absent) and not read in full by this page's author — treat as a pointer to look up, not as a verified figure.)) Whether an agentic browser can be trusted to express a consent choice is now both a methods question and a research topic. | * **LLM-driven banner interaction is unmeasured as an //instrument//, and alarming as a //subject//.** A language model that reads any banner in any language is the obvious successor to CSS-selector rule sets, and exactly one paper in this corpus puts an LLM anywhere near a consent artefact. Nobody has published cost, latency, determinism or accuracy against a hand-labelled set — and determinism is the hard one for a measurement instrument. Meanwhile the reverse question is opening up: work outside this corpus reports that browser-automation agents accept consent banners even when instructed to refuse everything.((Reported in a CHI 2026 Extended Abstracts paper on browser automation by LLM agents and consent, which measures agents defaulting to accept under explicit deny-all instructions. Not in this corpus (CHI is absent) and not read in full by this page's author — treat as a pointer to look up, not as a verified figure.)) Whether an agentic browser can be trusted to express a consent choice is now both a methods question and a research topic. |
| * **Consent measurement is about to be measuring a different law.** The ePrivacy Regulation proposal — the thing that was going to replace the 2002 Directive — was **withdrawn by the Commission in February 2025**, and the Digital Omnibus package tabled in November 2025 proposes moving the cookie rules into the GDPR itself. Neither is settled. A longitudinal consent study spanning 2025–2027 will straddle a change in the legal object it is measuring, and should say so.((The withdrawal and the Omnibus proposal are corroborated across independent policy trackers but were **not** verified here against a primary Commission document; treat the dates as approximate and check them before citing. The UK is a separate and firmer case: the Data (Use and Access) Act 2025 amended PECR to exempt some analytics and functionality cookies from prior consent, with the changes taking effect in early 2026 — also secondary-sourced here.)) | * **Consent measurement is about to be measuring a different law, and the primary documents exist.** The **Digital Omnibus** proposal, **COM(2025) 837 of 19 November 2025**, would insert a new **Article 88a into the GDPR** carrying "the consent requirement for the storing or accessing of personal data on the terminal equipment of natural persons" — that is, it moves the cookie rule out of the ePrivacy Directive and into the GDPR.((EUR-Lex, CELEX ''52025PC0837'', fetched 2026-08-19. The quoted phrase is from the Explanatory Memorandum's description of paragraph 12.)) The EDPB and EDPS jointly opined on it on **11 February 2026** (Joint Opinion 2/2026), supporting simplification but warning that splitting the cookie rules across instruments risks legal uncertainty.((''edpb.europa.eu'', "EDPB-EDPS Joint opinion 2/2026 on the Proposal for a Regulation as regards the simplification of the digital legislative framework (Digital Omnibus)", legislative opinion dated 11 February 2026. Fetched 2026-08-19. Its editorial note corrects the proposal reference to COM(2025) 837.)) **It is a proposal, not law**, and it is not settled. But a longitudinal consent study spanning 2025–2028 will straddle a change in the legal object it measures, and should say which regime each wave sits under. |
| | * **The UK has already moved, and by more than the EU has.** The Data (Use and Access) Act 2025 amended PECR to exempt several categories — including aggregate-statistics analytics — from prior consent, with effect from **5 February 2026**, and raised the maximum PECR fine from £500,000 to £17.5m or 4% of global turnover. The ICO's own storage-and-access guidance is being consulted on rather than settled.((The commencement date and the fine cap are corroborated across independent legal trackers; the ICO's guidance page confirms only that a revised version is out for consultation. **Not** confirmed here against the Act's own commencement regulations — check before citing. A UK-vantage crawl in 2026 is measuring a different rule from an EU-vantage one.)) |
| * **The reload effect has been measured once** {[rasaii2025_crumbs]}. If 25% of post-rejection change only appears after a reload, an unknown share of the published consent literature under-reports the effect of rejection. Which share is an answerable question. | * **The reload effect has been measured once** {[rasaii2025_crumbs]}. If 25% of post-rejection change only appears after a reload, an unknown share of the published consent literature under-reports the effect of rejection. Which share is an answerable question. |
| * **Consent revocation is nearly unstudied.** One paper {[kancherla2025_johnny]}, 158 sites. Withdrawal is as legally required as consent and is far harder to automate. | * **Consent revocation is nearly unstudied.** One paper {[kancherla2025_johnny]}, 158 sites. Withdrawal is as legally required as consent and is far harder to automate. |
| * **No shared benchmark exists.** There is no public, versioned set of annotated consent notices that a new detector can report against, which is why every paper reports precision and recall on its own hand-labelled sample and none of them are comparable. Building one would be a bigger contribution than most new detectors. | * **No shared benchmark exists.** There is no public, versioned set of annotated consent notices that a new detector can report against, which is why every paper reports precision and recall on its own hand-labelled sample and none of them are comparable. Building one would be a bigger contribution than most new detectors. |
| * **The reporting gap itself.** 44.2% of crawling papers say nothing about consent, and that has not improved since 2018. A one-line methods sentence would fix it; the question is why it does not. | * **The reporting gap itself.** On the audited figures, **94.4% of crawling papers leave the reader unable to tell what their crawl did with a notice**, and the share that does say is under one in ten even in the newest bucket. A one-line methods sentence would fix it; the question is why sixteen years of the field have not produced one. (The 44.2% ''not-stated'' row is the extraction's own count for that population and was **not** audited — after what the ''no-interaction'' audit found, no unaudited row on this page should be read as a claim about the papers.) |
| </wrap> | * **All 349 papers the extraction credits with a stated consent action have now been read**, so the figures above are hand verdicts rather than extractor output. What that cannot fix is the other direction: a paper that clicked a banner and never wrote it down is invisible here by construction, and the 495 ''not-stated'' and 236 ''not-applicable'' papers were **not** read — a false ''not-stated'' would be a further undercount. **32 is a floor on the true number of interacting papers, not an estimate of it.** Two of the three false negatives were found only because a named tool (BannerClick, CookieEnforcer) appears in the text; a paper that rolled its own clicking and described it in one unremarkable sentence would still be missed. |
| | </WRAP> |
| |
| ===== Related Pages ===== | ===== Related Pages ===== |
| * [[Privacy:Requests#Cookie Notices and Their Interactive Elements|Classifying Web Requests]] — detecting the notice and labelling its buttons, with the comparison table of detectors. | * [[Privacy:Requests#Cookie Notices and Their Interactive Elements|Classifying Web Requests]] — detecting the notice and labelling its buttons, with the comparison table of detectors. |
| * [[Privacy:Cookies|Classifying Cookies]] — what the cookies you observe before and after the click actually are, and the CookieBlock/Cookiepedia label sources. | * [[Privacy:Cookies|Classifying Cookies]] — what the cookies you observe before and after the click actually are, and the CookieBlock/Cookiepedia label sources. |
| | * [[Privacy:Policies|Measuring Privacy Policies and Terms]] — the long document behind the banner. A banner is a UI measurement; a policy is a document-retrieval and NLP measurement, with its own tool lineage and its own denominators, and the two literatures barely cite each other. |
| | * [[Privacy:TCF Consent Strings|Decoding TCF Consent Strings]] — the TC string and Google's Additional Consent string as artefacts: bit layout, where they hide, decoding them reproducibly, and what they do and do not prove. |
| * [[Programming:Interaction|Interaction with websites]] and [[Programming:Stateful Stateless|Stateful and stateless crawling]] — the crawler-side mechanics this page assumes. | * [[Programming:Interaction|Interaction with websites]] and [[Programming:Stateful Stateless|Stateful and stateless crawling]] — the crawler-side mechanics this page assumes. |
| * [[Programming:Crawler|Comparison of crawling libraries]] — which crawlers ship a consent-interaction step. | * [[Programming:Crawler|Comparison of crawling libraries]] — which crawlers ship a consent-interaction step. |
| * [[Design:Crawling location|Crawling location]] — why the vantage point changes which banner you get. | * [[Design:Crawling location|Crawling location]] — why the vantage point changes which banner you get. |
| | * [[Privacy:Age assurance|Age assurance]] — the other dismissable overlay on the first load, and one that usually writes a cookie //before// the banner is touched, so it is a confounder for anything counted pre-consent. |
| * [[Practices:Legal enforcement|Legal enforcement]] — what to do with a violation once you have found one, and which authority is competent. | * [[Practices:Legal enforcement|Legal enforcement]] — what to do with a violation once you have found one, and which authority is competent. |
| * [[Practices:Ethics|Ethics]] — clicking //Accept// at scale on behalf of nobody is a decision with an ethical dimension; it is discussed there. | * [[Practices:Ethics|Ethics]] — clicking //Accept// at scale on behalf of nobody is a decision with an ethical dimension; it is discussed there. |