Former San Francisco 49ers safety Eric Reid filed a collusion grievance against the National Football League.
"Our union is aware that Eric Reid and his legal representatives filed a collusion claim, which will be heard through the arbitration process as spelled out in our collective bargaining agreement," the NFLPA said in a statement to Jill Martin of CNN. "Our union supports Eric and we are considering other legal options to pursue."
Geragos confirmed the filing and the NFL declined comment on the matter, citing the confidentiality provision of the league's collective bargaining agreement, per Martin.
The 26-year-old LSU product became a free agent after finishing his rookie contract with San Francisco last season. He's yet to sign with a new team after six weeks on the open market.
Reid, who became linked to Kaepernick after they knelt together during the national anthem before games to protest social injustice in the 2016 season, is coming off a strong campaign with the 49ers.
He racked up 66 combined tackles, four passes defended, two interceptions and a fumble recovery across 13 appearances. Pro Football Focus graded him as the league's No. 30 safety.
Reid has yet to find a suitable offer despite that starter-level production, raising questions about whether his decision to protest is now costing him a job. Kaepernick, who started the movement in August 2016, has remained a free agent since opting out of his deal with the Niners in March 2017.
In March, Reid told Matt Maiocco of NBC Sports Bay Area he was prepared to accept his fate because he believes kneeling alongside Kaepernick was the right decision.
"I stand by what I've done," he said. "I know why I've done it. My faith in God is the reason. I can go to sleep at night confident I did what I was called to do. I'm just gong to stay positive and keep trying to stay in shape and wait and see what happens. I said at the end of last season I'm OK no matter what happens."
NFL commissioner Roger Goodell was deposed as part of the proceedings in Kaepernick's ongoing collusion case last month.