This week, three of the five people charged with May Day-related crimes were arraigned and pleaded not guilty. The fourth (Phillip Neel) wasn't able to attend because he's in Asia and had his date rescheduled for the end of the month. The fifth (Kellen Linnell) didn't show up. The court issued a warrant for his arrest.

The five have been charged with crimes including malicious mischief and riot. But what exactly does "riot" mean? It's not a charge you see very often.

RCW 9A.84.010:

(1) A person is guilty of the crime of riot if, acting with three or more other persons, he or she knowingly and unlawfully uses or threatens to use force, or in any way participates in the use of such force, against any other person or against property.

It's a broad charge—three people kicking just about anything counts as "riot"—but it's rarely applied.

Since riot is a gross misdemeanor, it would normally be handled by the city. Kimberly Mills at the city attorney's office says they've only charged one person with riot in the past five years, during a "West Coast Days of Action Against State Violence" protest near Seattle Central Community College in 2010.

In that incident, detective Rik Hall—whose name often turns up in reports and search warrants related to anarchist and radical-related crime/police activity—was dressed in plain clothes to watch the protest. His report says a mounted officer was hit in the back of the head with a paint-filled lightbulb. (The officer was wearing a helmet.) Det. Hall then saw five people dressed in black running away. Two ducked into Caffe Vita, then came out wearing plain clothes and carrying black clothes, which they threw into a trashcan.

Both were arrested and one was eventually charged with riot. (The charge was eventually dismissed as part of a plea involving another case.)

So much for the city attorney.

But because these May Day charges are bundled with some felonies, they've been filed by the county prosecutor.

Dan Donohoe at the prosecutor's office says they've only charged a handful of people with riot in the past 10 years: 15 charged in 2001, related to the Mardis Gras chaos in Pioneer Square; two charged in 2009 (he didn't have the details); and these five for May Day.

If the RCW for riot is so broad, why are charges so rare?

"The vast majority of cases we receive are not three people, it's one person," said Ian Goodhew, deputy chief of staff at the prosecutor's office. "And we often don't have evidence of the organized effort. Part of the uniqueness of this situation [May Day] is we have a heck of a lot of cameras around recording people's activity."

Those cameras, he says, show people clearly acting in concert—for example, wearing khaki pants and light-colored shirts, then stripping down to black, breaking (or trying to break) windows, and then changing their clothes again. "We're not just going out there and saying 'we found this blog post from seven weeks ago' for our evidence showing a concerted effort," he said.