He elaborated that the system could take the form of a browser plug-in, and that either the FTC or a private group could oversee it; beyond that, further details will have to wait until the FTC issues a report later this year about online privacy.
Even without all of the particulars, the concept of a do-not-track list seems likely to alarm many online ad companies, if for no other reason than because of telemarketers' experience with the do-not-call registry. That list, which has proven hugely popular with consumers, now has 200 million phone numbers.
But, while the phrase do-not-track might sound comparable to do-not-call, the concepts really aren't all that similar. People who sign up for the federal do-not-call registry are able to avoid most telemarketing -- including the much-disliked ringing telephone that interrupts dinner with an ad.
Do-not-track, on the other hand, wouldn't allow consumers to avoid advertising in the slightest. On the contrary, people would still see as many ads online as ever, but the difference is that ads wouldn't be targeted based on sites visited. So even Web users who dislike online ads might not join a do-not-track list if they decide they would prefer receiving targeted ads to run-of-network ones.
Additionally, many consumers already have the ability to place themselves on a do-not-track list of sorts by opting out of behavioral targeting, either through the Network Advertising Initiative's opt-out page, by using the group's browser plug-in, or on a site-by-site basis. While the NAI doesn't include all online ad companies, it counts at least 50 ad networks as members.
And even aside from the NAI opt-out page, consumers today can control much behavioral targeting through cookie settings in their browsers. Despite these tools, very few consumers seem to opt out of behavioral targeting.
Whether that will change with an FTC-backed do-not-track registry remains to be seen, but it's by no means certain that consumers would enlist themselves to the same extent as with do-not-call.