As reported in this NYT piece, the Pittsburgh police have arrested Elliot Madison for purportedly helping protesters evade arrest. The problem, of course, is that it is rather difficult to explain what makes Madison's tweets illegal other than it describes things that any person on the scene might describe. As described by the NYT:
Many of those messages tracked police movements. One read: “SWAT teams rolling down 5th Ave.” Another read: “Report received that police are ‘nabbing’ anyone that looks like a protester / Black Bloc. Stay alert watch your friends!”
One can imagine, if Twitter had existed in 1970, a prosecution for Tweeting "National Guard shooting into crowd! Watch your friends!" But, in any event, we seem to have lost our moral high ground in challenging Iranian police for arresting protesters who likewise "disobeyed a lawful order to disperse."