• by Wendy Davis , Staff Writer @wendyndavis, February 1, 2016

Online tracking expert Ashkan Soltani has departed from the White House Office of Science and Technology Policy after being denied security clearance.

Soltani, who announced his departure Friday via Twitter, said he wouldn't speculate on the reasons why he didn't obtain the clearance. But many industry watchers appear to think the move was in retaliation for helping the Washington Post interpret documents obtained by former NSA contractor Ed Snowden.

Journalist Barton Gellman, who wrote the Post's stories, responded to news about Soltani by tweeting that the privacy expert didn't himself leak any documents. "He made our NSA stories better & fairer -- and the workspace far more secure," Gellman said in a tweet. Those stories helped spur a new interest in encryption, resulting in Yahoo's decision to encrypt email by default.

Soltani joined the White House as senior adviser around six weeks ago, at the request of Chief Technology Officer Megan Smith. For one year prior to that, he served as chief technologist for the Federal Trade Commission.

His next career move isn't clear, but his Web site now describes him as "an independent researcher and technologist specializing on issues relating to privacy, security, and behavioral economics."

Before joining the FTC, Soltani spent many years shedding light on questionable online ad practices. For instance, Soltani reported in 2011 that the analytics company KISSmetrics tracked people using ETags, which store information in users' browser caches. If those users erased their cookies, they could be recreated with information from the ETags.

Within one week of Soltani's report, KISSmetrics not only stopped using ETags, but said it would allow people to opt out of tracking.

In 2009, he authored a report detailing Web companies' growing use of Flash cookies to track people who deleted their HTTP cookies. That report not only led to lawsuits, but eventually spurred Adobe to roll out tools that enabled people to more easily delete Flash cookies.

Soltani also helped the New Jersey Attorney General build a case against PulsePoint, which allegedly circumvented Safari users' default privacy settings, which block cookies by ad networks and exchanges. PulsePoint (formed by a 2011 merger of Datran Media and ContextWeb), agreed to pay $1 million and to implement a comprehensive five-year privacy program as a result of the probe.

State officials said in court papers that PulsePoint served an estimated 215 million ads to Safari users in New Jersey from June of 2009 through February of 2012.(PulsePoint said the cookies were set by predecessor company ContextWeb, and that PulsePoint executives weren't aware of the practice until February of 2012.)

Now that Soltani is no longer employed by the government, it wouldn't be surprising to see him again publicize new online tracking techniques that would otherwise remain secret.