The NFL Players Association filed a lawsuit against the NFL in U.S. District Court in Minneapolis on Monday to challenge an arbitrator’s ruling to uphold Adrian Peterson’s suspension by the league.

On Friday, NFL-appointed arbitrator Harold Henderson upheld Peterson’s suspension. The Minnesota Vikings running back was suspended until at least April of 2015 by commissioner Roger Goodell on Nov. 18, after Peterson failed to attend a disciplinary hearing regarding his alleged violation of the NFL’s personal-conduct policy.

The lawsuit comes as ABC News has obtained a recording of the Nov. 12 phone call between Troy Vincent and Peterson in which the NFL executive tells Peterson that he would be reinstated after a two-game suspension and get credit for his time on the commissioner’s exempt list.

According to ESPN, Vincent made the promise with the additional request that Peterson attend a meeting with Goodell to discuss the child abuse case in which he pleaded no contest in Texas to misdemeanor reckless assault for physically disciplining his 4-year-old son with a wooden switch. Peterson did not attend the meeting, however, and the NFL issued a six-game suspension to the running back days later.

The NFL Players Association had presented the phone call in its appeal of Peterson’s suspension, according to ESPN.

In the appeal heard by Henderson last week, the NFLPA argued that Goodell punished Peterson unduly under a revised personal-conduct policy.

In his ruling Friday, Henderson said, “I conclude that the player has not demonstrated that the process and procedures surrounding his discipline were not fair and consistent. He was afforded all the protections and rights to which he is entitled, and I find no basis to vacate or reduce the discipline.”

The NFLPA was not surprised by Henderson’s ruling.

In a statement Friday, the union said, “The NFLPA expected this outcome, given the hearing officer’s relationship and financial ties to the NFL. The decision itself ignores the facts, the evidence and the collective bargaining agreement. This decision also represents the NFL’s repeated failure to adhere to due process and confirms its inconsistent treatment of players. Our union is considering immediate legal remedies.”

Peterson was indicted in September on felony charges of reckless or negligent injury to a child after Texas authorities said he hit his 4-year-old son with a switch. He pleaded no contest to misdemeanor reckless assault on Nov. 4 and was ordered to pay a $4,000 fine and perform 80 hours of community service.