One of the most contentious issues surrounding online privacy centers on how much data companies should be able to collect after users say they don't want to be tracked.
Ad companies have said that they won't send those users targeted ads -- that is, ads that have been selected for users based on the other sites they've visited. Privacy advocates say that's not enough. They say that most data collection should stop -- though some would allow companies to continue gathering information for fraud prevention purposes or ad frequency capping.
That still leaves plenty of room for debate about matters like "market research," analytics, or other activities performed by online ad companies.
This week, Federal Trade Commissioner Julie Brill weighed in on the subject. In a speech delivered at the State of the Net West conference, Brill told ad networks they should spell out why they say they must collect market-research data from consumers who don't want to be tracked.
"On numerous occasions, the FTC and other stakeholders have asked the advertising networks for specific market research and product improvement uses that require retention of linkable consumer data," she said. "The advertising networks are the only ones who can make the case for such use; without input from them it will be hard to see how such uses can be justified when a consumer has opted out of tracking."
She also delivered a very practical warning to the ad industry: If people think their privacy is being violated, they will take matters into their own hands.
"I am concerned that, if consumers are not provided with an agreed-upon universal means to control the collection of their data, they will increasingly turn to other tools to prevent tracking," she said. "These 'self-help' tools are likely to be more blunt than what is currently under discussion."