The NFL Players Association, seeking a new arbitrator in the bounty case, says in a lawsuit that the league conducted a "biased" investigation and a "sham" arbitration process for three players suspended in connection with the New Orleans Saints' pay-for-play program.

The suit was filed Thursday in U.S. District Court and came two days after NFL commissioner Roger Goodell upheld the discipline he imposed on four current or former Saints players.

The union filed suit on behalf of itself and players Anthony Hargrove, Will Smith and Scott Fujita, saying they "suffered, and are suffering, irreparable and grievous injury with each day" their suspensions stand.

Hargrove, now with Green Bay, was suspended eight games while Smith received a four-game ban and Fujita, now with Cleveland, was hit with a three-game ban.

A fourth player, linebacker Jonathan Vilma, was suspended for the entire 2012 season and has sued the NFL and Goodell separately.

In a motion filed in the same New Orleans court on Thursday, Vilma asked for a temporary restraining order keeping the NFL from instituting its suspension against him while he works to have it overturned.

The suit filed on behalf of Hargrove, Smith and Fujita challenges Goodell's authority under the new collective bargaining agreement signed last year, saying it never agreed to have him arbitrate this type of player dispute and claiming he has no jurisdiction to do so.

It accuses Goodell of bias for publicly proclaiming the players' guilt before issuing his suspensions and says the follow-up process cementing those bans was bogus.

"Unfortunately," the suit says, "the investigation and arbitration process that the commissioner's public relations machinery touted as 'thorough and fair' has, in reality, been a sham."

The suit asks the court to invalidate Goodell's decision to uphold the bans and to select a neutral arbitrator in the case.

It says the league rendered its own arbitration process "a fraud" by refusing to provide the union with access to relevant evidence or witnesses "while at the same time utilizing hearsay and innuendo to smear and punish" Hargrove, Smith and Fujita.

As an example, the suit says the NFL rejected the union's request to have Joe Vitt available at the arbitration, but used a league lawyer's summary of the assistant coach's interview against the players.

Vitt, who later denied statements attributed to him by the NFL, has assumed the day-to-day duties of suspended head coach Sean Payton until he must serve his own six-game suspension once the regular season starts.

Vilma walked away from his appeal hearing with Goodell last month and didn't return for an afternoon session, saying he was discouraged by the process. A lawyer for the player called the hearings a "sham" and said the commissioner withheld evidence from the "supposed investigation."

Later that day, the NFL presented reporters with previously unseen evidence it collected in the case, including files showing details of the bounty program that were kept on a computer system.

The NFL revealed that much of its evidence in the investigation came from Vitt and former defensive coordinator Gregg Williams, who was hired by the Rams but suspended indefinitely for running the bounty program.