From the King County Prosecutor's office:
Joshua Garland, 28, was charged with one count of Assault Third Degree for allegedly grabbing a police officer's hand and twisting and pulling his arm. After reviewing video provided by Garland's defense attorney showing the alleged incident, prosecutors no longer believe they could prove the case beyond a reasonable doubt.
Andy Roberston, the attorney for Joshua Garland, tells me that the charge-dropping video comes from YouTube user seanbann, and shows Garland, at about :20 in, holding a large camera and wearing a black a bandana over his nose and mouth as he gets forcefully pulled behind police lines and arrested.
Garland is a photographer who goes by Alex (that's his middle name) and if you notice him wearing a gas mask beneath the black bandana, his attorney says that's "because he was pepper sprayed by police earlier in the day, while shooting photos."
Three other protesters still face charges of assaulting officers during the May Day protests, and are set to be arraigned on May 17.