NFL Media Insider Ian Rapoport reported Thursday that the NFLPA has filed its appeal for Adrian Peterson, per a source involved in the process. The argument is that the NFL did not act in a way consistent with the CBA's due process, per Rapoport.
Peterson had three days from his suspension, which was announced Tuesday, to file the appeal.
The union has also demanded a neutral arbitrator oversee the process, but that decision is up to Commissioner Roger Goodell, who, according to the collective bargaining agreement, would hear the appeal.
Peterson remains on the Commissioner's Exempt List during the appeal process. If the suspension is not overturned upon appeal the running back cannot be considered for reinstatement before April 15, 2015.