A court hearing Tuesday will address a claim by the NFL Players Association that the league colluded to set a secret salary cap in 2010.
Representatives from the NFL and the NFLPA will have 20 minutes apiece in oral arguments before a three-judge panel of the 8th U.S. Circuit Court of Appeals.
The NFLPA is appealing a ruling by U.S. District Judge David Doty in Minneapolis rejecting the union's attempt to reopen the Reggie White lawsuit that guided league labour matters from 1993 until the new collective bargaining agreement in 2011.
The union alleged owners used a covert cap to hold down salaries in the uncapped 2010 season. The players sought at least $4 billion US in damages.
Under terms of the current CBA finalized in 2011, players relinquished the right to sue on claims related to the case that carries the name of a two-time NFL defensive player of the year.
A ruling is not anticipated for a few months. The lawyer arguing the case for the NFL declined comment.
White filed a class-action lawsuit in 1993 seeking more open free agency and a salary cap. The resulting agreement was in place until 2008 when the NFL opted out, saying its costs were too high and that it needed givebacks from players.
Before the lawsuit, the NFL had limited free agency known as Plan B, in which teams were allowed to protect 37 players and had the right to match offers for free agents or receive compensation. White died in 2006.