The FBI's 2012 file on its Burning Man surveillance, obtained via Freedom of Information Act requests, reveals that America's domestic spy agency for at least five years, and has been using the event as an opportunity to try out its latest toys, with help from Pershing County sheriff's deputies.
Second item of interest is this paragraph, which could potentially imply that some burners were actually undercover police – sparking the debate over whether the term "plainclothes" applies in this situation.
"A cultural and artisan event" FBI files on Burning Man [JPat Brown/Muckrock]