• by Wendy Davis  @wendyndavis, July 7, 2013

Around one in five Web users now send a do-not-track request when they surf the Internet, according to Interactive Advertising Bureau general counsel Mike Zaneis. He adds that the IAB expects that proportion to increase to 50%.

Zaneis says that the high numbers of people with active do-not-track signals means that “it is no longer tenable” for the ad industry to allow consumers to opt out of online behavioral advertising by setting a do-not-track signal. Instead, the ad industry appears to be proposing to “de-link” or “de-identify” data about users who activate do-not-track headers. Such measures potentially could make it harder to determine people's names based solely on data about the Web sites they visit, but that depends on the methods used to “de-identify” the data.

Zaneis made the remarks on Wednesday, at a telephone meeting of the World Wide Web Consortium’s tracking protection group. The transcript reads as follows:

“My members seeing 20-25% of user base sending flag. Early on, our position had been: perhaps the W3C could standardize the DNT signal, and we would treat that as an industry opt-out.... That is no longer tenable.... We expect DNT:1 signals to approach 50% in short-term.”

The World Wide Web Consortium's tracking protection group -- made up of computer scientists , industry representatives and privacy advocates -- has spent two years trying to develop standards to interpret do-not-track commands in browsers. Currently, all of the major browser companies offer a do-not-track header. When activated, the header tells publishers and ad networks that users don't want to be tracked. But the header doesn't actually prevent tracking; instead, it's up to ad networks or publishers to decide whether to honor the header.

Last year, the umbrella group Digital Advertising Alliance said that it would honor do-not-track headers, provided that they were set by individuals and not turned on by default. At the time, observers interpreted this statement to mean that the ad industry would let consumers opt out of online behavioral advertising -- or receiving ads because they had visited particular sites in the past -- by setting a do-not-track header. Currently, the industry takes the position that consumers who want to opt out of behavioral advertising should click on a link that sets an opt-out cookie. But privacy advocates say that method is problematic, given that many consumers periodically delete their cookies. Privacy advocates also say that the ad industry should do more than just stop serving targeted ads to people who don't want to be tracked: The advocates say that ad companies should stop collecting data about those people.