NFL Players Accuse League of Collusion: What is Collusion?

It looks like the NFL labor situation is right back where it started. The NFL Players Association has sued the NFL for collusion, claiming that it imposed a secret salary cap during the 2010 season. That season, per the prior collective bargaining agreement, was supposed to be uncapped.
But the union claims that the teams and the league illegally agreed to impose a $123 million per-club salary cap. Representatives also claim the Redskins, Cowboys, Raiders and Saints did not abide by the agreement and were subsequently punished.
In this case, collusion is just another antitrust term. It describes a situation in which a group of people illegally conspire, or act in concert, to restrain competition. The NFL is accused of illegally conspiring to restrain salaries.
The NFL can't do this for one specific reason -- the Stipulation and Settlement Agreement (SSA). In 1992, a jury found the NFL to be in violation of the Sherman Antitrust Act. Players then filed a class action suit seeking injunctive relief. The SSA ended that suit, and it governs much of the NFL's labor costs.
The SSA specifically prohibits any NFL collusion. Under its terms, all 32 teams and the league are prohibited from entering into any agreement to restrict a club's ability to negotiate with a player with respect to the terms of employment. They are also prohibited from trying to circumvent this prohibition with respect to the salary cap.
If the NFL and team owners unofficially agreed to cap salaries during the 2010 uncapped season, then they most likely violated the terms of the SSA. They colluded, or conspired, to restrict one another's ability to negotiate players' salaries.
Even so, the players may not win their suit. The NFL claims that the collective bargaining agreement that ended last year's lockout prohibits the filing of these claims. If true, then it's possible nothing can be done about the alleged NFL collusion.
Related Resources:
- Collusion claim the latest NFL-union feud (Associated Press)
- NFL Players Association Accuses NFL of Collusion, Conspiracy (FindLaw's Courtside)
- NFL Lockout Extended: Does 8th Cir. Favor NFL Owners? (FindLaw's Tarnished Twenty)