The contentious relationship between the NFL and the NFL Players Association continued Wednesday when the union filed a federal lawsuit alleging the league and its owners conspired in collusion to establish a "secret $123 million salary cap" in 2010, which under the previous labor agreement was designated as an uncapped year of spending.

The NFLPA filed its collusion complaint in U.S. District Court in Minneapolis, claiming it falls under the supervision and oversight of Judge David Doty, who presided over the 1993 settlement of the Reggie White litigation case.

That settlement led to an unprecedented stretch of labor peace that lasted through 2010, designated as an uncapped year in which teams would not be restricted in their spending on players' salaries.

Instead, the NFLPA claims it learned on or about March 12 of this year that four teams -- the Washington Redskins, Dallas Cowboys, Oakland Raiders and New Orleans Saints -- did not abide by the NFL's secret rules that effectively advised teams to operate in 2010 under a $123 million salary cap.

The NFL in March penalized the Redskins and Cowboys in cap spending at $36 million and $10 million sums, respectively, during the next two years, a decision recently upheld by Special Master Stephen Burbank's ruling, citing the NFLPA's agreement to an arrangement that would redistribute the money to other teams for cap spending.

"The league expressed their view that they thought those teams had gotten a competitive advantage," NFLPA outside counsel Jeffrey Kessler said. "If we wanted other salary cap increases for the clubs [in 2012] ... the price for doing that was doing this salary cap reallocation.

"Had the union known about prior collusion, the union would never have agreed to these cap reallocations."

The union is seeking $1 billion in actual damages for players primarily in the 2010 free-agent class and $3 billion in damages as violation of the 1993 White agreement.