The head of the Senate’s powerful commerce committee said Friday he’ll introduce a bill that forces online advertising and tracking companies to let users easily opt out of online tracking.

Chairman Jay Rockefeller (D-West Virginia) said the bill, to be introduced next week, will create a “universal obligation for all online companies” to not track people who set a browser flag or cookie saying they don’t want to be tracked.

Rockefeller’s move complements a recent privacy bill introduced by Sens. John Kerry (D-Massachusetts) and John McCain (R-Arizona) that would enshrine a consumer bill on online rights, though it does not explicitly say that companies must obey the so-called ‘Do Not Track’ flag.

The Do Not Track flag is a simple idea that’s already been built into Firefox and IE9. If users choose to turn on the option, every time they visit a web page the browser will send a message to the site, saying “do not track.”

The next version of Apple’s Safari browser is expected to have the flag as well, but the feature is not on the road map of Google’s Chrome browser. Google, which runs the net’s biggest online advertising and tracking platform, says the meaning of the flag is too vague.

Currently, users who don’t want to be tracked by the net’s largest online advertisers need to visit the Network Advertising Initiative page to set opt-out cookies, which will be deleted anytime a user clears their cookies.

“Consumers have a right to know when and how their personal and sensitive information is being used online — and most importantly to be able to say ‘no thanks’ when companies seek to gather that information without their approval,” said Rockefeller in a press release. “This bill will offer a simple, straightforward way for people to stop companies from tracking their every move on the internet.”

According to Rockefeller, the bill will empower the FTC to go after companies that disobey the flag. Companies can collect info needed for their service to work from users who set the flag, but must destroy it or anonymize it once it’s no longer needed.

The likely winner if such a bill passes is oddly Facebook, since the company targets its ads based on the information that users explicitly provide it, which puts it beyond the bill’s reach. Google faces the most risk, since, depending on the bill’s wording, it could apply not only to its far-reaching advertising network, but also to its collection of user’s search terms.

While Rockefeller promises the bill will be universal, it’s not clear how any such legislation could apply to companies outside the United States.

An even more stringent House bill prohibiting online tracking was introduced in February by Rep. Jackie Spears (D-California), who made a name for herself getting privacy legislation passed in California’s legislature.

Critics of the Do Not Track idea argue that it’s still unclear what counts as tracking and that mass adoption of the setting will harm innovation on the web, as many services and publications rely on the higher payouts of targeted ads to provide free information and services to users.

Photo: U.S. Sen. Jay Rockefeller (D-West Virginia) Chairman of the of the Senate Committee on Commerce, Science and Transportation, makes a point during the nomination hearing for Dr. Elizabeth M. Robinson, nominee for Chief Financial Officer for NASA, Thursday, Oct. 15, 2009, on Capitol Hill in Washington. Photo Credit: (NASA/Paul E. Alers)