14 DAY TRIAL // Mozilla has been working on a new way to deal with third-party cookies, those set by sites that you didn't actually visit. Recently, Mozilla decided to block all third-party cookies, like Safari does, and only allow those from domains users went to.
But that plan was flawed and put on hold. Blocking indiscriminately would lead to plenty of false positives and would also not fix some of the problems.
Instead, Mozilla, Opera, and Stanford, all part of the Do Not Track group, are now putting together a Cookie Clearinghouse which will keep track of both allowed and banned cookies.
The idea is to have a central repository which would dictate which cookies, regardless of whether they are from a different domain or not, can be set by websites and which can't. This would deal with both types of problems.
One problem with the simple blocking system was that sites sometimes use more than one domain. Many rely on a CDN to house static content. For example, Facebook stores images with fbcdn.net. The site needs to be able to set cookies affecting both domains and from both domains.
The other problem is that, even if you agree with cookies from one domain in one setting, you may not agree with it in another. For example, you may want Google to set cookies from the search page, but not from a +1 button found on the web.
Under the Cookie Clearinghouse model, all of these cases would be covered. There are, of course, more things to determine; whether to allow analytics cookies or not, for example. This is why Mozilla and everyone else involved wants to keep the discussion open; it wants input from all sides of the industry.
That said, this approach has a much bigger chance of success than Do Not Track for one simple reason – it doesn't not rely on websites complying with some rules. Browsers can enforce a cookie policy, but they can't enforce Do Not Track.