Peter Schaffer says the suit will seek to retrieve financial damages resulting from the suspension. Along with the suit, Schaffer also plans to file a motion for preliminary injunction, asking the court to allow Browner to become a free agent on March 11, which would have occurred had he not been suspended.
Browner's appeal was denied by the league, leading to the indefinite suspension. Browner would have to apply for reinstatement to the league after sitting out a season.
Last December, Browner was suspended indefinitely without pay for violating the NFL's substance-abuse policy by testing positive for marijuana. He missed the last two games of the regular season and Seattle's run to the Super Bowl title.
In 2012, Browner was suspended the final four games of the regular season for violating the league's policy on performance-enhancing drugs. That suspension is separate from the league's substance-abuse program.
Schaffer, a practicing attorney in Colorado, said he intends to file suit in that state. Colorado is one of two states to legalize marijuana for medical and recreational use. Washington is the other.
A spokesperson for the NFL said the league will not comment on the issue.
The focal point of Schaffer's argument is that the violations that led to Browner being one strike away from an indefinite suspension occurred while he was not employed by the NFL.
Browner ran afoul of the substance-abuse policy during his first stint in the league with Denver, but he was released before the start of the 2006 season and therefore was not subject to a suspension.
No other team signed Browner, and he went on to play four seasons with the Calgary Stampeders of the CFL before signing with Seattle at the beginning of the 2011 season.
Schaffer said he will argue that Browner was subject to periodic drug testing by the NFL even though he was no longer part of the league, and that both the league and the players' association failed to notify his client of mounting penalties and suspensions due to his failure to submit to testing while he played in the CFL.
Because of the neglected drug tests, the league placed Browner in Stage 3 of its drug program when he joined the Seahawks in 2011.
"I'm old school," Schaffer said. "Why would an employer be allowed to have post-employment restrictions on an employee? Why would an employer be able to do that?"
Even though he did not play in the Super Bowl, Browner said via Twitter that he will receive a Super Bowl ring from the organization.
A Pro Bowler in 2011, Browner turns 30 in August. He is in Southern California working out with the hope of getting back on the field in 2014, according to Schaffer.
"Brandon has really matured as a young man," Schaffer said. "I've been impressed with how he's handled every step of this tragic tale. It's almost Shakespearian."