Posted on June 15, 2012
This wiki is intended as a repository for discussion and documentation related to this claim.

Statement of Mozilla on Patent Claim related to Do Not Track

Several members of the W3C Tracking Protection Working Group have recently been approached by Peter Cranstone, the CEO of 3PMobile. Mr. Cranstone claims that his patent, U.S. Patent No. 8,156,206 (the "'206 patent") covers the Do Not Track specification that is being developed by the W3C (the "W3C DNT specification").

Based upon a thorough analysis by independent patent counsel, Mozilla concluded that the ‘206 patent did not cover the W3C DNT specification because the specification did not satisfy all of the limitations of the claims. We also believe there is prior art that invalidates the claims. If anyone has additional prior art (software, documentation, papers that describe DNT before February 6, 2006 that describe setting browser privacy settings that results in the transmission of a HTTP header field with those privacy settings), please reference it here via this public wiki.

In a welcome and positive gesture of good faith, Mr. Cranstone indicated that he was willing to grant Mozilla a free license. We offered that the best way to help was to make sure that everyone had the same license opportunity without having to negotiate a non-standard license agreement. We suggested that the existing W3C RF license provisions would be best so that everyone would obtain real RF license rights consistent with other web standards and without one-off license arrangements.

Mr. Cranstone declined the W3C RF approach and maintains that claim 22 of the ‘206 patent covers the W3C DNT specification. While Mozilla disagrees with his contention, if Mr. Cranstone would provide a claim chart detailing how claim 22 covers the W3C DNT specification, everyone could better understand his position. Given his reluctance to provide a true RF license, the ultimate motivations seem unclear. If he wants to maintain the ability to license some claims on a royalty basis that do not relate to the W3C DNT spec, we do not see any reason that cannot be achieved. 


Often patent applicants will take new market and technical developments and amend their pending patent applications to cure the deficiencies in the patent. For this reason, it does not seem prudent to go into detailed non-infringement positions without further assurances from Mr. Cranstone about his pending applications.

If Mr. Cranstone intends to provide a RF license for DNT, we applaud him and remain happy to work with him to find the right form whether it be a covenant not to sue, statement, or other license structure, but it has to work for everyone and be free of unnecessary representations and conditions.

Prior Art

[Please provide references to materials that establish prior art related to Do Not Track here]

W3C Composite Capability/Preference Profiles (CC/PP)

• 2.0 Recommendation Last Call (4/30/07)
• 1.0 Recommendation (1/15/04)
• Exchange Protocol Note (6/24/99)

Behavioral Advertising Opt Out

• Tacoda ETag Opt-Out Supercookie (11/06)
• Network Advertising Initiative Opt-Out Cookies (7/00)

Session Initiation Protocol (SIP)

• RFC 3325: Private Extensions to SIP (11/02)

Usenet X-No-Archive

• Deja News (Internet Archive) (12/23/96)

W3C Platform for Privacy Preferences (P3P)

• 1.1 Note (11/13/06)
• 1.0 Recommendation (4/16/02)