The two-year-old drive to give consumers a simple way to block companies from tracking their behavior as they move across the Internet has faltered, say participants in the process who are struggling to reconcile privacy concerns with an advertising model that pays for many free Internet services.
The friction puts in peril the "Do Not Track" initiative that appeared to have widespread support at a White House event in February, when industry officials endorsed it in concept. Federal Trade Commission Chairman Jon Leibowitz, who also embraced the idea as central to the independent agency's push for protecting personal data privacy, had predicted a deal by the end of the year.
But meetings of a key working committee have turned acrimonious in recent months, and a co-chair of the effort plans to step down Wednesday. Participants now say a deal remains months away, and some say it may take federal action to limit Internet tracking.
"This thing has stalled, and there has been deliberate obstructionism by some segments of the advertising industry, and there is great frustration because of this," said John M. Simpson of Consumer Watchdog, one of several privacy advocates working on the issue.
The idea for a Do Not Track system was inspired by the popular "do not call" lists that have curtailed telemarketing calls, but there have been sharp disagreements about how to build a system that limits tracking without undermining advertising revenue.
Industry groups voluntarily adopted a version last year giving consumers the ability to block advertising based on their Web browsing history. Officials from the Digital Advertising Alliance, which organized the effort, said that nearly 20 million users have visited the site at youradchoices.com and that more than 1 million have chosen to opt out of ad tracking.
But privacy advocates have called this system hard to use and too permissive in the information it allows marketers to collect. The two sides have clashed repeatedly in meetings of a working committee of the World Wide Web Consortium, a group that was charged with negotiating policies on how to implement a Do Not Track system. The consortium sets industry standards for the Web but has struggled to handle this issue.
"That process has not gone particularly well," said Stuart P. Ingis, a Washington-based lawyer representing the Digital Advertising Alliance. He welcomed Wednesday's planned resignation of co-chair Aleecia McDonald, a Stanford privacy researcher, as an opportunity to jump-start the process.
McDonald, who will remain a member of the 97-person committee, said she favored new leadership overseeing a process that has become "very contentious" in recent months but has developed renewed energy since President Obama's reelection. "We've seen a resurgence of interest," she said, adding, "We're not going to get it done by January 1st."
She is likely to be replaced by Peter Swire, an Ohio State University law professor who was a chief counselor for privacy in the Office of Management and Budget during the Clinton administration, say people familiar with the matter who spoke on the condition of anonymity because the decision was yet to be finalized.
Most browsers already have settings allowing users to request that advertisers not track them, but the practical impact of such systems has been small. Microsoft announced in May that it was shipping the latest generation of its Internet Explorer browser with the Do Not Track setting on as a default, angering the advertising industry, which favors a system in which consumers must personally choose to block ads.
The controversy highlighted how little agreement there is on the issue. The various groups negotiating the terms of Do Not Track have not definitively settled on exactly what the term means, what kind of data collection should be prohibited or even how the consumer preference should be communicated to advertising networks.
The versions favored by most privacy advocates would block not only the serving of ads based on individual Web browsing history but also the collection of any kinds of personal information for marketing purposes.
Jonathan Mayer, a Stanford graduate student and privacy advocate serving on the working committee, said the industry's voluntary system does not go far enough to protect consumers. "It has kind of a fox-guarding-the-henhouse quality," he said.