Mark Zuckerberg doesn't want to talk about tracking users who've logged out of Facebook

For someone whose entire fortune depends on online advertising, Mark Zuckerberg sure is reluctant to talk about it.

Over the course of his Tuesday testimony in front of a joint hearing of the Senate Judiciary and Commerce Committees, Facebook's CEO was asked by Sen. Roger Wicker (R-Miss.) whether or not the company can track users even when they have logged out of the service.

"There have been reports that Facebook can tracks a user's internet browsing activity even after that user has logged off of the Facebook platform," stated Senator Wicker. "Can you confirm whether or not this is true?"

The company can, of course, track non-users of its platform via social plugins and cookies. In February of this year a Belgium court ruled that this practice was illegal. And in 2015, a group of researchers stated "Facebook users who are logged-out from Facebook are still being tracked through the social plug-ins."

But Zuckerberg didn't feel like talking about this, apparently.

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"Senator, I want to make sure I get this accurate so it would probably be better to have my team follow up afterwards," he replied.

"You don't know," asked Wicker.

"I know that people use cookies on the internet, and that you can probably correlate activity between, um, between sessions," responded Zuckerberg. "We do that for a number of reasons, including security and including measuring ads to make sure that the ad experiences are the most effective."

So Zuckerberg said his company correlates activity between sessions, but he didn't get into the specifics of what exactly that means. Does that mean activity taking place between sessions, i.e. when a users is logged out? It's not exactly clear what he was getting at, which was maybe the point.

What we do know, however, is that in July of 2017 a U.S. judge dismissed a case claiming that Facebook was tracking users after they had logged out. Specifically, reported The Guardian at the time, judge Edward Davila dismissed the case because the company's "intrusion could have easily been blocked, but plaintiffs chose not to do so.”

In other words, the judge didn't say Facebook wasn't doing it, but rather that it the plaintiffs could have prevented it.

So that appears to be your answer, Senator Wicker. Figure it out, and stop it, on your own.