“”SWAT teams rolling down 5th Ave. … Report received that police are nabbing anyone that looks like a protester. … Stay alert watch your friends!” Pennsylvania State Police arrested New York social worker Elliot Madison last month for being part of a group that posted messages like those on Twitter. The arrest took place in a Pittsburgh motel during protests at the Group of 20 summit. In all, almost 5,000 protesters demonstrated throughout the city during two days, and about 200 were arrested for disorderly conduct.

But Madison wasn’t among those protesting on the street. Instead, published reports say he was part of a behind-the-scenes communications team using Twitter to “direct others, specifically protesters of the G-20 summit, in order to avoid apprehension after a lawful order to disperse.” A week later, FBI agents spent 16 hours in Madison’s home executing a search warrant for evidence of federal anti-rioting law violations.”