According to Newsday, the New York Civil Liberties Union has asked the Nassau County Police Department to investigate its use of horses to control the crowd during the protest just prior to the third and final US Presidential debate at Hofstra University in Hempstead on October 15, 2008.
The investigation appears to be centered on what happened after the arrests, and whether or not the mounted police put veterans and civilians at risk by using their horses to maintain control, resulting in injuries to at least three people.
A major question appears to be whether or not the injuries took place in the street, or on the sidewalk. Police made it clear to spectators that the sidewalks were "free speech zones," but protesters were not permitted in the street.
Photos and video taken at the scene reveal a partial glimpse of the melee, and its bloody aftermath.