• by Wendy Davis , Staff Writer @wendyndavis, June 6, 2012

Microsoft's surprise move last week to break ranks with other Web companies by turning on do-not-track in Internet Explorer 10 is still causing considerable angst in the industry.

Assuming that ad companies respect browser-based settings, Microsoft's decision transforms online behavioral advertising into an opt-in system for IE10 users -- marking a dramatic departure from longstanding standards allowing behavioral targeting as long as users can opt out.

But there's no guarantee that ad networks will honor IE10's headers. While the umbrella group Digital Advertising Alliance said in February that it will require members to follow browser-based do-not-track requests, the group also imposed conditions on that promise. One of them was that users themselves select do-not-track.

The DAA condemned Microsoft's move, as did groups ranging from the Association of National Advertisers to the Direct Marketing Association to the privacy company TRUSTe.

On Tuesday, TRUSTe CEO Chris Babel wrote in a blog post that Microsoft's new do-not-track setting "will be confusing to consumers who have historically had default internet browser choices set to open, with the ability to adopt more restrictive limits."

That post prompted Microsoft associate general counsel Mike Hintze to tweet on Wednesday, "TRUSTe's view: browser settings should be defaulted to least privacy possible. Burden on users to protect privacy."

He said in a follow-up tweet, "Every default setting is making a choice for the consumer. Consumer can change it. Only [difference] is we chose privacy by default."

So far, however, Microsoft hasn't persuaded too many other Web company executives.

Today, some members of the Internet standards group World Wide Web Consortium expressed disapproval of Microsoft's move, according to a summary of a telephone conference call.

Some participants in the call said that a browser-based do-not-track setting shouldn't be turned on by default -- though the language used in the write-up of the call indicates that not everyone agrees.

"Today we reaffirmed the group consensus that a user agent MUST NOT set a default ... unless the act of selecting that user agent is itself a choice that expresses the user's preference for privacy," reads a summary of the conference call. "In all cases, a DNT signal MUST be an expression of a user's preference."

That phrasing appears to pave the way for arguments that users make a choice by selecting a certain browser, or software that automatically turns on do-not-track.

The W3C is still sorting out the issue. Meanwhile, some participants apparently expressed the remarkable opinion that Microsoft itself could face a Federal Trade Commission inquiry for activating do-not-track by default.

"Implication A: Microsoft IE ... will not be able to claim compliance with DNT once we have a published W3C recommendation," reads the summary of the phone call. "If they claim to comply with the W3C recommendation and do not, that is a matter the FTC (and others) can enforce."

Of course, it seems unlikely that the FTC would ever sue Microsoft for enabling do-not-track by default. That representatives from other ad and tech companies could even raise the prospect shows just how unnerved they must be by Microsoft's move.