The NFL players' union came to the defense of embattled Dallas Cowboys running back Ezekiel Elliott by suing the league in an attempt to vacate his upcoming six-game suspension for domestic violence.

The suit, which was filed in federal court in Texas, claims the league's appeal process was 'fundamentally unfair' since the arbitrator, Harold Henderson, denied a request to have the accuser, Elliott's ex-girlfriend Tiffany Thompson, testify at Thursday's hearing.

Elliott was suspended in early August after the league's year-long investigation concluded he used physical force against Thompson in the summer of 2016, prior to his rookie season. However, Elliott denied the allegations under oath during the appeal hearing, according to the lawsuit, and Ohio prosecutors declined to pursue the case last year, citing conflicting evidence.

Dallas Cowboys running back Ezekiel Elliott (above) was suspended six games by league commissioner Roger Goodell for violating the NFL's policy on domestic violence

Elliott's ex-girlfriend Tiffany Thompson (above) claims the Dallas Cowboys star abused her

The NFLPA's lawsuit also claimed that NFL commissioner Roger Goodell and other league executives hid information that was favorable to Elliott's case.

'In what may mark one of the most fundamentally unfair arbitral processes conceivable, Elliott and the Union were subjected to an arbitration process in which, among other things, there was a League-orchestrated conspiracy by senior NFL executives, including NFL Senior Vice President and Special Counsel for Investigations Lisa Friel, to hide critical information—which would completely exonerate Elliott,' read the NFLPA's petition.

The lawsuit accuses Friel of withholding from Goodell the word of co-lead investigator Kia Roberts, who the suit says concluded that the accuser wasn't credible and that discipline wasn't warranted.

'The withholding of this critical information from the disciplinary process was a momentous denial of the fundamental fairness required in every arbitration and, of course, does not satisfy federal labor law's minimal due process requirements,' the lawsuit said.

Henderson is supposed to rule on the NFL's decision to suspend Elliott 'as soon as practicable,' according to the labor agreement.

The NFL had medical experts examine photos of bruising that was allegedly caused by Elliott, but the lawsuit claimed that the doctors questioned could not definitively rule that the injuries were caused by domestic violence.

According to Deadspin, the filing read: 'Ultimately, it was established that neither doctor could rule out the fact that the bruises depicted were consistent with numerous other possible causes from the allegations of abuse, including drunken and drug-induced falls, fights with other persons, rough sex and other possible causes.'

Elliott might be eligible for the season opener against the New York Giants on Sept. 10 since his representatives plan to file a temporary restraining order, according to the lawsuit.

According to Elliott, Thompson intended to 'ruin' his life after he tried to break up with her, as reported by The Fort Worth Star-Telegram.

'You are a black male athlete,' Elliott claimed Thompson told him, according to the report. 'I'm a white girl. They are not going to believe you.'

Thompson posted photographs to Instagram last year of bruises that she claims were caused by Elliott

The lawsuit claims that the two doctors questioned could not rule out the possibility that the bruises were consistent with other possible causes apart from the allegations of abuse

The NFL's personal conduct policy was amended three years ago to stiffen penalties in domestic cases. Friel was hired as a result of the changes, which came after NFL was sharply criticized for its handling of a case involving former Baltimore running back Ray Rice.

'You are a black male athlete,' Elliott claimed Thompson told him, according to the report. 'I'm a white girl. They are not going to believe you.'

The lawsuit also cited Henderson's refusal to require Goodell to testify. According to the labor agreement, Goodell can choose from a list of arbitrators for appeals.

Henderson has heard dozens of appeals, including New Orleans running back Adrian Peterson's in a child abuse case out of Texas when Peterson was with Minnesota. Henderson denied Peterson's appeal of a suspension, but a federal judge overturned Henderson's ruling.

The lawsuit claims that Roberts' conclusions weren't shared with four outside experts who advised Goodell before the ruling, and the suit makes broad claims of a 'league-orchestrated conspiracy by senior NFL executives.'

According to the letter Elliott received informing him of the suspension three weeks ago, the NFL believed he used 'physical force' three times in a span of five days in a Columbus, Ohio, apartment last July resulting in injuries to Thompson's face, neck, shoulders, arms, hands, wrists, hips and knees.

Prosecutors in Columbus decided about a year ago not to pursue the case in the city where Elliott starred for Ohio State, but the NFL kept the investigation open. The league said its conclusions were based on photographs, text messages and other electronic evidence.

The lawsuit says Roberts prepared a document detailing inconsistencies in the accounts of Thompson, who the suit said was interviewed six times by Roberts.

'Presumably, the commissioner would have reached a very different disciplinary conclusion - one of exoneration and no discipline - had he known about the evidence which Friel and other unidentified, high-ranking NFL executives chose to conceal from the disciplinary process,' the lawsuit said.