I admit to being a bit surprised that some here don't consider the events in LA a riot. Yes under the constitution you are allowed to "peacefully assemble". Burning cars, looting, and dropping concrete blocks onto passing cars from a bridge doesn't qualify as a peaceful demonstration.
Three decades OTJ I've worked in a couple of "minor" riots. If your the guy surrounded by a hundred "protesters" trying to literate your lawfully arrested prisoner its an entirely different point of view. Have you ever been the target of hundreds of rocks and bottles thrown at you at 1 AM by a unruly crowd? With the nearest patrol car two blocks away due to the size of the "crowd"? Then had to fight your way back to the car carrying said prisoner?
If you haven't been there, done that, you don't know jack ****. Pretty freakin' simple.
In New Jersey where I worked it is defined as, "four or more participating in a course of disorderly conduct..." look up, N.J.S.A. 2C:33-1.
I'd say hundreds or thousands more than qualify.