Summary

  • The W3C's Do Not Track design let a browser send DNT:1 to express a user's preference against tracking on a request. The same design offered sites a Tk response field and status resource to describe their own behavior.
  • The specification governed expression and reporting, while compliance behavior belonged to separate regimes. After Candidate Recommendation snapshots in 2015 and 2017, the W3C retired the work on 17 January 2019, citing insufficient deployment of the extensions as defined.

A request header with a political job

In December 2010 testimony, the U.S. Federal Trade Commission supported a browser setting that would persist and convey a consumer's choice to sites. The agency described legislation or enforceable self-regulation as possible ways to make that choice consequential. The proposal placed a visible decision where a person browsed. It still needed a rule at the other end of the connection.

The W3C's Tracking Preference Expression gave the request a precise shape. DNT:1 meant the user preferred not to be tracked on that request; DNT:0 meant the user preferred to allow tracking. A general-purpose browser's default was unset unless the user's choice of browser itself implied a preference. The specification also described user-granted exceptions, a script-readable preference and ways for a site to report tracking status, including the Tk response header. The browser could express a preference repeatedly. The server could answer with a status. Collection changed when recipient behavior or an applicable rule carried that exchange into practice.

The switch stayed on the recipient's side

The W3C text assigned the mechanics of communicating compliance while leaving the actual requirements for compliant conduct to other regimes. A server receiving DNT:1 therefore had a clear signal and a vocabulary for its reply; the consequences of that signal depended on rules outside this protocol. The FTC had imagined a browser choice with teeth. The technical standard could carry the choice across the network, but could not manufacture the teeth through an HTTP field alone.

The W3C publication history shows Candidate Recommendation snapshots in August 2015 and October 2017, followed by retirement on 17 January 2019. The final Working Group Note says the extensions, as defined, had not achieved enough deployment to advance and that the group was ending its work. The group's own page records the same closure date and lists both the expression and companion compliance work among retired specifications. A snapshot is evidence that a design was offered for implementation; the 2019 note is the institution's record of how that effort ended.

The bargain was lopsided in one precise place. Sending a preference was a browser task. Changing tracking behavior sat with the recipient and any applicable compliance regime. Contemporaneous client and server measurements would show how often the signal was sent and honored; the W3C's final note establishes its narrower finding about deployment of these extensions. The wire could carry “no.” The switch still needed someone willing or required to throw it.

Sources