• by Wendy Davis , Staff Writer @wendyndavis, April 3, 2015

Changing course, Microsoft said today that it will no longer activate do-not-track signals by default in its browser.

“As industry standards evolve, how we implement those standards evolve as well,” Microsoft's chief privacy officer Brendon Lynch says today in a blog post announcing the move.

The decision marks a significant shift from 2012, when Microsoft stunned online ad companies by announcing it would turn on the signals automatically. That move initially struck some observers as pro-privacy. But it ended up backfiring, because the decision made it easy for ad companies to justify ignoring the settings on the grounds that they didn't reflect users' choices.

Do-not-track headers tell publishers and ad networks that users don't want their Web activity recorded and used for marketing purposes. The industry already allows people to decline behaviorally targeted ads, but the industry run opt-out mechanism involves setting opt-out cookies. The problem for users is that those opt-outs disappear when people shed their cookies.

By contrast, browser-based commands persist regardless of whether people clear their cookies.

But browser-based do-not-track commands don't actually prevent tracking. On the contrary, ad networks and publishers are free to ignore the signals -- and many do so.

One reason why few companies now honor the signals is that the industry hasn't yet finalized efforts to implement them. The Internet standards group World Wide Web Consortium has tried for many years to figure out how publishers and ad networks should respond to do-not-track signals, but those efforts are still ongoing.

Today's move by Microsoft is “probably helpful” to the W3C's initiative to standardize do-not-track, says Justin Brookman, who chairs the W3C's Tracking Protection Group. “If DNT is a clear affirmative choice in all browsers, it's harder for companies to credibly ignore the signals,” he says in an email to MediaPost.

Microsoft itself seems to realize that its former approach likely hindered efforts to implement an industry-wide program.

“Put simply, we are updating our approach to DNT to eliminate any misunderstanding about whether our chosen implementation will comply with the W3C standard,” Lynch writes today. The W3C's current draft says that the signals must reflect users' preferences, as opposed to choices made by vendors. “Without this change, websites that receive a DNT signal from the new browsers could argue that it doesn’t reflect the users’ preference, and therefore, choose not to honor it,” he writes.