The Patriots could cite language that was built into the contract as grounds not to pay the $10 million. A clause said the team could void guaranteed money if the player "takes any action that materially undermines the public's respect for, or is materially critical of, the club, the player's teammates, or the club's ownership, coaches."
Brown was named in a lawsuit filed one day after he signed with New England that alleged him of raping his former personal trainer. Other accusations of misconduct surfaced in the following days.
The Patriots released Brown on Friday. Earlier in the week, Brown appeared to send threatening texts to a woman who accused him of making an unwanted sexual advance while she was contracted to paint a mural in his Pennsylvania home in 2017.
The NFL Players Association will represent Brown in his grievance.
Before joining the Patriots, the Oakland Raiders used fines to void $30 million guaranteed on his deal with them. Brown declared Sunday morning on Twitter that he won't play in the NFL again due to the canceled agreements.
Although he's being sued, Brown has never been arrested or charged in any cases related to sexual misconduct. The seven-time Pro Bowler continued his Twitter tirade in a series of since-deleted tweets by pointing to other high-profile NFL figures who didn't lose their jobs in the wake of sexual misconduct allegations against them.
One of the tweets referred to Patriots owner Robert Kraft, who was charged in February with soliciting prostitution at a Florida spa. The woman accusing Brown of rape is pictured in the post.
Another tweet singled out Hall of Fame tight end and FS1 personality Shannon Sharpe, who's been particularly critical of Brown for his off-field behavior since at least last year.
Brown also referenced Pittsburgh Steelers quarterback and former teammate Ben Roethlisberger, who was suspended six games - eventually reduced to four - for violating the NFL's personal conduct policy in 2010.
Brown's agent, Drew Rosenhaus, said Saturday that teams have shown interest in signing Brown but are waiting for his legal situation to play out. The 31-year-old led the NFL in receiving twice and touchdown catches once over his 10-year career.