Foxborough police arrested 264 people at the 2013 County Music Festival, less than half the number arrested at last year's two-day event.
Thousands of country music fans attend the annual event at Gillette Stadium.
NBC 10's I-Team obtained records showing that police arrested 375 people during County Fest in 2011 and 567 people in 2012.
The I-Team found in both cases, about 80 percent of those arrested were taken into protective custody, and never charged with any criminal act.
Police claimed those suspects were incapacitated and a danger to themselves and other fans.
Several of the suspects filed a class-action lawsuit, claiming the arrests violated their civil rights.
The lawsuit is working its way through the federal court system. A judge may make a decision early next year.