I hope everyone realizes that it's well established in LE use of force policies that shooting first is perfectly legal (which is true even for private citizens). If, from your perspective, an individual has the opportunity, ability, and intent to cause serious bodily harm or death, you are well within your rights to use deadly force. That means you don't have to wait for them to shoot first. For the most part, this is a great thing. It means that if someone breaks into your house and points a gun at you, you can shoot them dead. If they don't get a shot off...oh well. The problem is, in this case, if a cop sees one of the marchers even just swat at a fly that landed on his arm, it could be easily articulated as a pre-assault indicator to justify shooting. You know it's wrong, I know it's wrong, but the shoot will be ruled to be justified and the media will paint the LEO's as heros. It really doesn't matter who shoots first.