Since declining his option for the 2017 season with the San Francisco 49ers back in March, veteran quarterback Colin Kaepernick has remained readily available on the NFL free-agent market.

However, he has yet to receive significant interest from any team around the league outside of a visit with the Seattle Seahawks during the summer. With that in mind, the 29-year-old has decided to file a grievance against NFL owners, according to Ian Rapoport of NFL Network.

This all but confirms that notion that Kaepernick has come to terms with the belief that he's getting blackballed by the league because of his political stance. There have been several instances where he could have possibly been an option for a few teams looking for backups due to injury, but none have made him an offer.

The decision to file a grievance could make things extremely interesting over the next few days, as it could create more conflict in his attempt to get back into the league. That said, he has already received support from the NFLPA, voicing that he had their backing in his push to earn another opportunity to play in the NFL.

Things could hit high gear in the coming days as the NFL owners will likely release a statement to the claim against them.