Colin Kaepernick has filed a grievance under the collective bargaining agreement against NFL team owners for collusion, reports Mike Freeman of Bleacher Report.

Kaepernick has hired high-profile attorney Mark Geragos and is preparing to release a statement about his grievance soon, added Freeman.

The free-agent quarterback has remained unemployed since opting out of his contract with the San Francisco 49ers in March and has garnered little interest from teams around the league.

This has caused some to suggest he's being blackballed for his national anthem protests during the 2016 season.

Kaepernick appeared in 12 games for 49ers in 2016, throwing for 2,241 yards with 16 touchdowns to four interceptions.

His 90.7 passer rating ranked 17th in the league, ahead of 10 quarterbacks who were starters going into the 2017 season.