On Thursday, I had the opportunity to moderate a session on behavioral profiling in online advertising at the Computers, Freedom, and Privacy Conference  in Montreal. Due to delays in the morning, the session lasted only just over an hour rather than an hour and half, but even with the fully allotted time I don't think we could have addressed all of the complexities of this subject -- much more discussion is necessary. Chris Hoofnagle from the Samuelson Law, Technology, and Public Policy Clinic at Berkeley started things off with an overview of the advertising landscape, noting that advertising is regulated in many mediums -- billboards, TV, radio -- so the idea of advertising regulation is nothing new. What is new, however, is the range of technologies and systems available that allow individuals to be profiled and targeted. Kim Howell of Microsoft followed up on Chris's introduction. Kim discussed some of the technical details of how behavioral profiling can work and how Microsoft's advertising products work. She noted, for example, that only Internet users who sign into Microsoft's Windows Live system have behavioral profiles developed about them. This is the kind of detail that CDT thinks should be more involved in the public debate about behavioral targeting, and it's the sort of thing we would like to see discussed at an FTC workshop  on the issue. For the second half of the session I moderated a discussion between Mike Zaneis of the Internet Advertising Bureau and Jeff Chester of the Center for Digital Democracy. There weren't too many points of agreement between these two, but the discussion managed to raise many questions that we hope will continue to fuel this dialogue: When is an opt-in regime necessary? How can notice be crafted in an understandable and functional way? What constitutes "sensitive" information? What should the standards be for granting Internet users access to the profiles built about them? Our session was too short to answer these and many of the other questions that were raised, but as the online advertising landscape continues to grow and evolve, so too will the debate about behavioral profiling.