Truly silly. Halvar Flake, a German security expert planning to do a training to Blackhat attendees (a number of whom are federal security officials, no less), has been refused access to the United States over a technicality (despite never having had such a problem before):
For the next 4 1/2 hours I was interviewed about who exactly I am, why I am coming to the US, what the nature of my contract with Blackhat is, and why my trainings class is not performed by an American citizen. After 4 hours, it became clear that a decision had been reached that I was to be denied entry to the US, on the ground that since I am a private person conducting the trainings for Blackhat, I was essentially a Blackhat employee and would require an H1B visa to perform two days of trainings in the US.
Unfortunately, it’s not often within the purview of bureaucrats to work within the “spirit of the law”. One can only hope that Halvar can appeal to some reason at the consulate.