Ravens' Jackson receives 4-game ban

Baltimore Ravens rookie cornerback Asa Jackson has been suspended four games by the NFL for violating its policy on performance-enhancing substances.

The fifth-round pick out of Cal Poly will miss the final three games of the regular season and if Baltimore clinches a playoff spot, he'll be eligible to return to the active roster one day after the club's first postseason game.

The Ravens enter Week 15 in control of the AFC North Division, holding a two- game lead over both Pittsburgh and Cincinnati.

Jackson has been used only on special teams in the past three games, registering one tackle.