The Dolphins suspended Incognito indefinitely 11 days ago for "conduct detrimental to the team", and the offensive tackle loses $235,294 (£146,410) for every game which he misses.
However, the maximum a player can be suspended for detrimental conduct is four games, per league rules. For a ban to last longer, it must be imposed by the league itself.
The NFL Players Association statement regarding the grievance said via NFL.com: "Richie Incognito filed a non-injury grievance against his employer, the Miami Dolphins, pursuant to his rights under the Collective Bargaining Agreement.
"The grievance challenges his suspension for conduct which was alleged to have occurred while he was with the club and Incognito requests that the hearing be held on an expedited basis so that he can immediately resume playing for the team. The NFL Players Association will continue to protect the rights of all players."
On the field, the Dolphins are 4-5 and sit third in the AFC East.