Vontaze Burfict, the Oakland Raiders linebacker with a history of hard hits that skirt the line of legality, was suspended on Monday for the remaining 12 games of the N.F.L. season.

It was the longest suspension ever for on-field actions, NFL.com reported.

Burfict’s penalty was for “repeated violations of unnecessary roughness rules,” but it was precipitated by a helmet-to-helmet hit on tight end Jack Doyle of the Indianapolis Colts on Sunday.

“Your contact was unnecessary, flagrant and should have been avoided,” Jon Runyan, the N.F.L. vice president for football operations, wrote in the ruling.

The hit came in the second quarter of a victory over Indianapolis. Doyle caught a pass at midfield, and Burfict, with head lowered, plowed his helmet into Doyle’s. He was whistled for a 15-yard unsportsmanlike conduct penalty on the play and ejected from the game.