ST. LOUIS — St. Louis Rams running back Steven Jackson can become a free agent after the 2012 season under the contract that he renegotiated before the team's season opener in early September, CBSSports.com reported Thursday.

The Rams and Jackson's agent, Eugene Parker, were working on a contract extension for the three-time Pro Bowler.

Unable to reach an agreement, they came up with an unusual compromise.

Jackson can void the final year of his five-year contact. He'd previously failed to reach the incentives necessary to void the final two years of the deal.

The new contract reportedly still pays Jackson $7 million this year and $7 million next year if opts not to void it.

Jackson, who has been slowed by a groin injury, was active for the Rams' game against the Arizona Cardinals on Thursday night.

The Rams' other inactives were: wide receiver Steve Davis, safety Matthew Daniels, running back Terrance Ganaway, defensive tackle Matthew Conrath, offensive tackle Rodger Saffold, defensive end Eugene Sims and quarterback Austin Davis.

Defensive tackle Darnell Dockett (hamstring) was active for the Cardinals.