• by Wendy Davis , Staff Writer @wendyndavis, February 2, 2011

The prospect of an easy-to-use browser-based opt-out for behavioral advertising advanced this week with Mozilla's release of a preliminary version of a do-not-track header.

But this newest tool is only an early -- and potentially buggy -- version of the header. An even bigger obstacle for people who want to test the feature is that it's still unknown whether ad networks will honor it.

While none have publicly said they won't, the ad industry's official position appears to be that consumers don't need the new tool because the new self-regulatory program allows users to opt out of tracking through links at AboutAds.info, the Network Advertising Initiative, and the new forward-i icons. So far, consumers can opt out of tracking by around 60 ad networks and other tracking companies (out of an estimated 300) at AboutAds.info and the NAI sites.

Despite the opt-out links available through the sites run by self-regulatory groups, as a practical matter ad networks might be well served to also honor do-not-track headers, especially if they gain traction with users.

Consider, the industry currently faces the prospect of regulation. Rep. Bobby Rush (D-Ill.), who introduced privacy legislation last year, has said that he intends to reintroduce his bill this week.

Additionally, the Federal Trade Commission is considering whether to recommend that Congress pass legislation requiring companies to offer a do-not-track option. That proposal was endorsed last weekend by The New York Times.

Of course, new regulations might be passed whether or not ad networks honor do-not-track headers. But deciding to ignore such headers will almost certainly fuel calls for new laws.

Additionally, ad networks almost certainly risk lawsuits if they deliberately ignore a do-not-track header. These days tech-savvy consumers have a variety of methods for determining cookies are being dropped on their machines. And consumers also have access to a growing number of class-action attorneys willing to file privacy lawsuits against online ad companies.

In the last several years, Web users have brought privacy lawsuits against a broad array of companies including Facebook, Google, SpecificMedia, Quantcast, Rapleaf, Zynga and the now-defunct NebuAd.

Consumers have alleged everything from violations of the federal wiretap law to computer fraud to violations of state consumer protection laws. Some legal experts have questioned whether the Web companies really broke the law with the features, but some companies -- including Google and Facebook -- nonetheless agreed to seven-figure settlements.