MINNEAPOLIS (WCCO) — A district court judge is now being asked to throw out Adrian Peterson’s season-ending suspension.

In Minneapolis on Monday, the NFL Players Union (NFLPA) sued the league in hopes of having a judge stay the arbitrator’s decision to uphold Peterson’s indefinite suspension by the NFL.

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Also on Monday, audio recordings were released revealing a phone conversation between the Vikings running back and the NFL’s Troy Vincent, a league official who reportedly suggested Peterson’s penalty would be less harsh.

The league decided to sideline the star player indefinitely in November after he disciplined his son with a wooden switch last spring in Texas. Peterson entered a no contest plea in a Texas court.

On Friday, arbitrator Howard Henderson upheld the leagues suspension of Peterson.

When the NFL slammed the door Dec. 11, essentially giving Peterson no hope of returning this season, the NFLPA lawsuit was already in the works.

“I think that they’ve made the strongest possible argument that they can make,” says Joe Daly, a Hamline University professor emeritus of law.

Daly is an authority on arbitration law and acts himself as an arbitrator in union and management disputes. He says while Peterson’s petition is strong, attempts to overturn arbitration awards rarely succeed.

“The U.S. Supreme Court and the Minnesota Supreme Court have ruled time and again that we simply do not overturn arbitrator’s decisions,” he said.

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However, Daly says there are a few exceptions when it can be shown a party ignores the language of a collective bargaining agreement, or uses an “evidently partial arbitrator.”

The petition calls arbitrator Harold Henderson’s award, “defective.” It also says the NFL defied the fundamental “principles of notice, fairness and consistency.”

But perhaps its strongest argument will be the partiality of Henderson, a former league executive.

However, a smoking gun in the union’s case could be the recorded telephone call between Adrian Peterson and the NFL’s Football Operations chief, Troy Vincent.

The audio, aired on ABC’s Good Morning America on Monday, seems to support Peterson’s belief that his suspension would be for two games — and two games only.

Peterson is heard asking, “I get two games?” To which Vincent replies, “Yeah.”

Attorneys for Peterson and the players association are asking for an expedited hearing on the matter. They contend that Peterson suffers irreparable harm each day the arbitration award remains in effect.

A hearing will have to be scheduled in U.S. District Court in Minneapolis soon after the league attorneys have a chance to view the petition. They will have three days to respond.

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As for his future, Peterson will turn 30 next March and he indicated to a sports reporter over the weekend that he’s even contemplated retirement.