Citing statements made by New York Giants owner John Mara, the NFL Players Association claims league owners conspired to keep salaries lower in a year that was supposed to be "uncapped" under the terms of the then-effective 2006 collective bargaining agreement.
"We cannot stand by when we now know that the owners conspired to collude," NFLPA Executive Director DeMaurice Smith said.
The claims are "without merit" and not allowed under the new labor deal, league spokesman Greg Aiello wrote on his Twitter account.
The suit, which claims league owners arbitrarily imposed a salary cap of $123 million per team for the year, cites statements by Mara following an NFL move this week to penalize the Dallas Cowboys and Washington Redskins for "front-loading" player contracts into the "capless" 2010 season.
"What they did was in violation of the spirit of the salary cap," the NFLPA quoted Mara as saying. "They attempted to take advantage of a one-year loophole ... full well knowing there would be consequences."