Free agent safety Eric Reid wants the NFL's new collective bargaining agreement invalidated over language added following ratification of the pact earlier this month.
He is calling for an investigation and a re-vote.
In a letter to the NFLPA on Monday, Reid's lawyers said language posted on the players association's website after passage of the agreement by a 1,019-959 vote on March 15 contains different language than the one players signed off on.
The new CBA is set to begin with the upcoming 2020 season and extend through 2030.
The letter from attorneys Ben Meiselas and Ray Genco highlight a difference in wording in the section about the league's disability plan that affects hundreds, and potentially thousands, of ex-players who applied for Social Security disability insurance payments before Jan. 1, 2015. In the version the players received and approved, those offsets applied only to players who applied after Jan. 1, 2015.
In a series of tweets Monday, Reid, a vocal opponent of the agreement, provided screenshots of the CBA agreement that showed the language added after players approved the deal.
The NFL declined comment and the NFLPA did not respond to a request for comment on Reid's letter or say why the language was modified after the vote.
Meiselas told The Associated Press by phone Monday that the discrepancy was discovered when lawyers were "working with families of disabled players to guide them through the process."
"We've been obviously critical of the CBA from the outset because it takes from disabled players. And so in advising them, we were looking at it and pointing out where they had issues and where they were going to be likely getting less money," Meiselas said. "And then we saw it, and we go, 'I don't remember seeing this in Paragraph B.'"
Meiselas questioned why the language was added and why the NFL and players' union weren't transparent about the change.
"And so Eric's letter demands the invalidation and an investigation and a re-vote because how do you stick in language that players didn't know they were voting for?" Meiselas said. "It's perplexing and concerning even if the changes were minor that there was no transparency and no explanation. But here, the changes are major and drastically and dramatically impact disability benefits to players."
He said a re-vote seems like "the only logical answer."
"When there's a potential manipulation of the language to an agreement, what's the alternative?" Meiselas said, adding, "We're waiting on an explanation at this point."