Williams can't play this season without penalty

Running back Ricky Williams, who informed the Miami Dolphins last month that he was retiring, has filed the necessary paperwork with the NFL Management Council. The filing will mean that he cannot play this season if he chooses to return to football.

David Cornwell, general counsel to sports agent Leigh Steinberg, filed Williams' retirement papers late last week with the NFL Management Council. It was necessary for Williams to file such papers because he was in the NFL substance-abuse program. He filed as a way to tell the league officially that he no longer would be subject to random drug testing.

Under league rules, if a player in its substance-abuse program files retirement papers, he cannot unretire for a year without penalty. If he unretires in less than a year, it's counted as a positive drug test in the NFL program -- which, in Williams' case, would be his fourth positive test and would result in an indefinite suspension.

If Williams unretires after a year, he still would be facing a four-game suspension, having now, according to him, recently tested positive for marijuana for a third time under the NFL's testing program. A third positive test brings with it a mandatory four-game suspension.

Information from ESPN's Hank Goldberg and Chris Mortensen was used in this report.