Do Not Track: It’s the user’s voice that matters

Alex Fowler

Today, Microsoft announced a change in how it will be implementing Do Not Track (DNT) in Internet Explorer. In a pre-release version of IE10, Microsoft will automatically start sending a DNT header on behalf of its users to not be tracked by third parties across the Web.

We appreciate seeing Microsoft putting its full weight behind DNT, especially given Firefox was the lone browser supporting DNT just one year ago. This will make DNT more mainstream and bring more attention to the important issue of user control.

We look forward to learning more about Microsoft’s new DNT implementation, as well as its implications for the standards work currently underway. And for the Web community, we thought it would be helpful to share our position, as well as the consensus view of the W3C Tracking Protection Group, about how we believe DNT can be most effective.

At its foundation, DNT is intended to express an individual’s choice, or preference, to not be tracked. It’s important that the signal represents a choice made by the person behind the keyboard and not the software maker, because ultimately it’s not the browser being tracked, it’s the user. In the words of the W3C group, which is made up of leading consumer privacy groups and industry representatives including Microsoft:

“Key to that notion of expression is that it must reflect the user’s preference, not the preference of some institutional or network-imposed mechanism outside the user’s control.” (Tracking Preference Expression, W3C Editor’s Draft, 29 May 2012)

DNT is not an off switch for a particular technology, rather it is the expression of an individual user’s desire being reflected in code — and that’s what makes the feature great. Do Not Track transcends specific technology and gets to the heart of what matters: how a user’s browsing habits are used.

There are three different signals to consider in broadcasting the user’s preferences for tracking:

  1. User says they accept tracking
  2. User says they reject tracking
  3. User hasn’t chosen anything

Firefox defaults to state 3: we don’t know what the user wants, so we’re not sending any signals to servers. This causes the presence of the signal to mean more — the signal being sent should be the user’s choice, not ours. Therefore, Firefox doesn’t broadcast anything until our user has told us what to send.

DNT allows for a conversation between the person sitting behind the keyboard and the site that they want to visit. If DNT is on by default, it’s not a conversation. For DNT to be effective, it must actually represent the user’s voice.

We introduced DNT to do just that: to give users a voice and let them tell sites that they don’t want to be tracked. We did this before knowing exactly how sites and advertisers would respond, and we still believe this is the most effective way for DNT to work.

Update (5-June): We’ve received a few comments asking if we believe all privacy defaults should be about letting users decide, even when that approach leaves users vulnerable. The short answer is “no”; our approach to DNT should not be viewed as a broad policy statement that will apply to other privacy and security considerations — our choice of opt-in for DNT is specific to the way the DNT feature works.

In carefully weighing our approach for appropriate DNT defaults, we talked with many members of the Mozilla community, privacy and technical experts and our users. The DNT feature relies on representing each individual’s desire to web sites, something that requires each user to activate the feature. In fact, a number of academic studies have found that there are users interested in personalized services and content, including targeted ads, so they would not like to have the header sent for them by default. Taken together, we believe the right starting point for a DNT system is a default of preference unknown.

Sid Stamm & Alex Fowler