Free agent quarterback Colin Kaepernick is pursuing a collusion grievance against the NFL under the CBA, according to Jason La Canfora of CBS Sports and Mike Freeman of Bleacher Report.

The NFL spokesman told La Canfora that he is checking on it.

Kaepernick remains a free agent since opting out of his contract with the San Francisco 49ers in March. Kaepernick was one of the NFL's biggest stories in 2016 after he decided to kneel during the national anthem to protest and raise awareness against racial injustice in America. Players throughout the league have continued protesting during this NFL season.

As explained by Sports Illustrated's Michael McCann in March, "Collusion occurs when two or more teams, or the league and at least one team, join to deprive a player of a contractually earned right. Such a right is normally found in the collective bargaining agreement signed by a league and its players’ association. For example, the right of a free-agent player to negotiate a contract with a team cannot be impaired by a conspiracy of teams to deny that a player a chance to sign."

• Does Colin Kaepernick have a legit collusion case?

Kaepernick has hired attorney Mark Geragos, who has represented high profile clients including Michael Jackson, Winona Ryder and NASCAR driver Jeremy Mayfield. Geragos issued the following statement:

"We can confirm that this morning we filed a grievance under the CBA on behalf of Colin Kaepernick. This was done only after pursuing every possible avenue with all NFL teams and their executives.

If the NFL (as well as all professional sports leagues) is to remain a meritocracy, then principled and peaceful political protest -- which the owners themselves made great theater imitating weeks ago -- should not be punished and athletes should not be denied employment based on partisan political provocation by the Executive Branch of our government. Such a precedent threatens all patriotic Americans and harkens back to our darkest days as a nation. Protecting all athletes from such collusive conduct is what compelled Mr. Kaepernick to file his grievance.

Colin Kaepernick's goal has always been, and remains, to be simply be treated fairly by the league he performed at the highest level for and to return to the football playing field."

According to Adam Schefter of ESPN, the NFLPA released a statement saying it would assist Kaepernick in this process and will talk with him soon.

The statement reads:

"Our union has a duty to assist Mr. Kaepernick as we do all players and we will support him.

The NFLPA has been in regular contact with Mr. Kaepernick's representatives for the past year about his options and our union agreed to follow the direction of his advisors throughout that time.

We first learned through media reports today that Mr. Kaepernick filed a grievance claiming collusion through our arbitration system and is represented by his own counsel. We learned that the NFL was informed of his intention to file a grievance before today.

We are scheduling a call with his advisors for early this week."