As his representatives initiated an appeal, Peterson remained at the centre of an escalating argument between the league and the NFL Players Association over the player discipline process.
Commissioner Roger Goodell told Peterson on Tuesday he will not be considered for reinstatement before April 15 for his violation of the NFL personal conduct policy. Peterson pleaded no contest Nov. 4 to misdemeanour reckless assault in Texas for injuries to his 4-year-old son with a wooden switch.
The NFLPA quickly called for a neutral arbitrator to handle an appeal and sharply rebuked the league for what it labeled as inconsistency and unfairness in determining the discipline. The NFL's words were even stronger, with a nearly 1,600-word statement spelling out the conditions for Peterson's return to the field and describing the reasons for the punishment.
The NFL said Peterson would stay on the special exempt list and continue to be paid during the appeal process, but the union's attempt to at least temporarily reinstate him failed. The grievance filed against the league last week was overturned Tuesday by the arbitrator who heard the arguments, according to a person with knowledge of the situation. The person spoke to The Associated Press on condition of anonymity because of the sensitivity of the situation.
Even if Peterson were to win a shorter suspension with an appeal, the Vikings actually playing him would be an implausible scenario given the heat they have taken and the long time Peterson has been away from the team. The Vikings have six games left and host the Green Bay Packers on Sunday.
The Vikings issued only a brief statement: "We respect the league's decision and will have no further comment at this time."
Fullback Jerome Felton said on Twitter that characterizing his feelings on the NFL's decision as a disagreement would be the "understatement of the year." In Pittsburgh, Steelers safety Mike Mitchell questioned the system that gives Goodell executive power on player discipline.
"I'm not just trying to bash him or come down on him, but I think players would feel better if he wasn't just judge, jury and executioner," Mitchell said.
Peterson has said he intended no harm to his 4-year-old son, only discipline. Peterson was on a special exempt list at the sole discretion of Goodell, essentially paid leave while the case went through the legal system.
The NFLPA said Peterson was told that would count as time served toward a suspension, citing an unidentified NFL executive. League spokesman Brian McCarthy said the stay on the exempt list was taken into account, citing "aggravating circumstances" for the extended suspension.
Goodell announced Aug. 28 tougher punishment for players involved with domestic violence. That action stemmed from a torrent of criticism for the initial leniency toward Baltimore Ravens running back Ray Rice following a caught-on-camera knockout punch of the woman who is now his wife. Rice was later suspended indefinitely and recently had his appeal heard by an arbitrator.
According to the enhanced policy, first offences of assault, battery or domestic violence bring a six-game suspension.
Goodell's letter to Peterson cited the "aggravating circumstance," pointing to the child's age and the significant physical difference between him and his son.
"Further, the injury inflicted on your son includes the emotional and psychological trauma to a young child who suffers criminal physical abuse at the hands of his father," Goodell wrote. "Second, the repetitive use of a switch in this instance is the functional equivalent of a weapon, particularly in the hands of someone with the strength of an accomplished professional athlete."
Goodell also came down on Peterson for showing "no meaningful remorse" for hurting the boy and expressed concern that he "may feel free to engage in similar conduct in the future."
The injuries to the boy occurred in May. Peterson was indicted in September, a few days after the season opener. The Vikings put him on the inactive list for the next game. The day after, they announced he would resume playing until completion of his due process in court.
But with the Rice backlash as a backdrop, Peterson, the Vikings and the NFL were inundated by protests as corporations cancelled sponsorships. The Vikings relented and less than two days later he was placed on the exempt list.
The union has accused the league of overstepping bounds spelled out in the collective bargaining agreement.
"The decision by the NFL to suspend Adrian Peterson is another example of the credibility gap that exists between the agreements they make and the actions they take. Since Adrian's legal matter was adjudicated, the NFL has ignored their obligations and attempted to impose a new and arbitrary disciplinary proceeding," the NFLPA said.
Peterson's salary for the season was $11.75 million. He will keep the money accrued while on the exempt list. But the NFL's punishment has now amounted to a 14-game ban, with six unpaid weeks. That's the equivalent of a fine of more than $4.1 million.
Peterson will turn 30 in March. There are three years and $45 million remaining on his contract, but none of it is guaranteed. The Vikings would take only a $2.4 million hit on their 2015 salary cap if they cut him before next season.
AP Sports Writer Will Graves in Pittsburgh contributed to this report.
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