The NFL Players Association faces significant legal obstacles, experts say, in its bid to win damages from the league via a lawsuit that accuses the 32 teams of colluding to hold down player salaries in 2010, when there was no NFL salary cap.

For starters, the league contends that the union doesn’t even have the right to bring the case.

“I understand the union’s argument,” said Gary Roberts, dean of the Indiana University law school. “Certainly, superficially there’s some evidence to support it. But you have to get past the first procedural issue of whether they have waived their right to bring the claim.”

Other legal and business experts said the union’s task is difficult but perhaps not impossible.

“Collusion is very, very difficult to prove,” said David Carter, executive director of the sports business institute at the University of Southern California. “It takes an awful lot of connecting of dots that might or might not exist. It’s a tall order.”

The players’ union filed its collusion lawsuit Wednesday in federal court in Minnesota, alleging that the NFL operated with a secret salary cap of $123 million per team in 2010, the uncapped year. NFL teams are barred from conspiring to restrict players’ salaries. The union is seeking at least $1 billion in damages.

The league denied the collusion accusations and maintains that the union is prohibited from filing its lawsuit by a provision of the collective bargaining agreement reached in 2011 and an agreement filed in court last year.

Experts predicted that the NFL will attempt to have the lawsuit dismissed on those grounds and said the league has a strong case.

“Even if the [players association] believes they have strong evidence of collusion, they still have to overcome a very large threshold of whether they have waived their right to bring this case,” said Gabriel Feldman, director of the sports law program at Tulane University. “Initially they are going to be arguing over whether there is a right to bring this claim.”

An article in the CBA prohibits the union from filing “any claim relating to. . . collusion with respect to any league year prior to 2011.”

Jeffrey Kessler, an attorney for the union, said this week he does not believe the CBA article prohibits the filing of the collusion lawsuit because the union did not know at the time the labor deal was completed that collusion had occurred and therefore was not aware such a claim was possible.

In addition, the two sides filed a court document last year that says: “The parties stipulate to the dismissal with prejudice of all claims, known and unknown, whether pending or not, regarding the stipulation and settlement agreement…” The document specifically mentions a case related to the league’s television contracts and a previous collusion claim by the union.

But Kessler said that broad dismissal of all claims known and unknown was rejected by the court and the court instead dismissed only existing claims. The league contends that the original wording was accepted and applies now.

“It’s very broad language,” Feldman said. “When you read it, your first reaction is that it appears to block the PA from bringing these claims. But the PA has a different interpretation of the language. I can’t handicap it. It’s an uphill battle for the PA but they do have an interpretation that they are going to offer that would enable them to bring the claim.”

Not enough is known yet, Roberts said, about the strength of the union’s case if the complaint is not dismissed.

“Once you get to the merits, it will turn on the evidence,” Roberts said. “It’s not a frivolous complaint on its face. I think it will gain some traction. But there are an awful lot of unanswered questions at the moment.”

The Minnesota federal court in which the case is filed often has been depicted as a favorable legal venue for the union. But the federal appeals court that would be the next step in the legal process regularly is portrayed as business-friendly. Experts expressed mixed views about the importance of that, ranging from saying it matters little during the dismissal debate to expressing confidence the union will prevail at the district court level but the league will win on appeal.