The ruling means the NFL Players Association has lost the non-injury grievance it filed against the NFL on behalf of Peterson.
Earlier Tuesday, the league announced Peterson has been suspended without pay for the remainder of the season for violating the NFL's personal conduct policy. Peterson, who is expected to appeal the suspension, now must remain on the Exempt list until his appeal is heard. He has three business days to appeal and will continue to be paid pending a decision.
Peterson was indicted on felony charges of reckless or negligent injury to a child in September. On Nov. 4, he pleaded no contest to misdemeanor reckless assault after authorities said he hit his 4-year old son with a switch. He was ordered to pay a $4,000 fine and perform 80 hours of community service.
The NFLPA criticized the league for what it called an "arbitrary disciplinary proceeding" after Peterson's legal matters had been already resolved.
The league held a hearing over conference call on Monday to determine whether Peterson should be further punished under the league's personal conduct policy. The decision was made by Das.
The NFL said in a statement that Peterson showed no remorse for his conduct.
The league also took issue with Peterson's use of a switch to punish his son, saying the tree branch was equivalent to a weapon, "particularly in the hands of someone with the strength of an accomplished professional athlete."
Peterson has missed the Vikings' last nine games after his indictment. Since Peterson was placed on the Commissioner's Exempt list, he must be reinstated before he is allowed to play again. On Nov. 6, the NFL announced that Peterson's case would be reviewed for potential discipline under the personal conduct policy and asked him to submit any relevant information.
Peterson did not show up for an NFL disciplinary hearing on Friday. Peterson said he never agreed to the meeting because when he consulted with the union, he found the hearing was "something new and inconsistent with the CBA" and told the NFL he would not participate.
"It is imperative that you avoid any incident of this kind in the future,” Goodell stated in his letter. "Any further violation of the Personal Conduct Policy will result in additional discipline and may subject you to banishment from the NFL."
- Molly Geary and Sarah Barshop