Study finds 12.5% of companies violating own do-not-track policies

The Do Not Track efforts led by self-managed advertising groups aren't going as well as some might hope, with at least eight participating companies continuing to track users across the Web even after they opt out. The finding highlights the weaknesses of an entirely voluntary system: just because the companies say they will do it doesn't necessarily mean that they will.

The Network Advertising Initiative (NAI) is one of several self-regulating groups aimed at adopting voluntary codes of conduct when it comes to advertising to users online. Late last year, those groups (including the NAI) announced that they would begin pushing the Advertising Option Icon, an icon that is meant to let users know which sites are participating in behavioral tracking. Users would then be able to easily opt out of any behaviorally targeted advertising if they so choose. Collectively, the groups represent some 5,000 other companies that advertise online, though use of the icon itself is voluntary as long as they offer the opt-out functionality.