A federal judge has cleared the way for Minnesota Vikings running back Adrian Peterson to be reinstated, ruling that an NFL arbitrator "failed to meet his duty" in a child abuse case that shook the league.

U.S. District Judge David Doty issued his order Thursday, less than three weeks after hearing oral arguments. Doty overruled NFL arbitrator Harold Henderson's denial of Peterson's appeal.

The league suspended Peterson through at least April 15 under its personal conduct policy. But Doty said in his 16-page ruling that Henderson "simply disregarded the law of the shop and in doing so failed to meet his duty" under the collective bargaining agreement.

NFL spokesman Brian McCarthy said the league will "review the decision."

NFL Players Association executive director DeMaurice Smith said in a statement the decision was a "victory for the rule of law, due process and fairness."

The crux of the issue was the application of the enhanced personal conduct policy, increasing a suspension for players involved with domestic violence from two games to six games. Because that was implemented after the injuries occurred to Peterson's son, delivered by a wooden switch that Peterson was using for discipline, the union contended that the prior standard of punishment should apply.

"Our collective bargaining agreement has rules for implementation of the personal conduct policy and when those rules are violated, our union always stands up to protect our players' rights," Smith said. "This is yet another example why neutral arbitration is good for our players, good for the owners and good for our game."

Doty's courtroom has long been a ground zero of sorts for NFL labor matters, and his ruling pattern has favored the union more often than not.

The increased penalty for domestic violence arose from the furor over the league's handling of former Baltimore Ravens running back Ray Rice, who was seen on surveillance video knocking out the woman who's now his wife with a punch in an elevator.

Rice was initially suspended for two games before Commissioner Roger Goodell declared the ban indefinite. The arbitrator who heard Rice's appeal, former U.S. District Judge Barbara Jones, ruled that Goodell's decision was "arbitrary" and an "abuse of discretion."

Despite the NFL's argument that the ruling by Jones was irrelevant to Henderson's, Doty disagreed.

"The court finds no valid basis to distinguish this case from the Rice matter," Doty said.

Now there's the matter of Peterson's future with the Vikings.

He's under contract through 2017, carrying a $15 million salary cap hit for 2015, and several high-ranking Vikings officials have said definitively they want him to return. General manager Rick Spielman said last week he expects Peterson to be back. But Peterson has expressed some uneasiness, telling ESPN in a recent interview he felt betrayed by the organization during the process of Goodell placing him on paid leave while the child-abuse case played out in court in Texas.

The market opens with the new league year March 10, at which time the Vikings could trade Peterson if they so decide. If they cut him, they'd owe him no more money and take only a $2.4 million hit to their salary cap.

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