With Nick Fairley and Mikel Leshoure being arrested twice each this offseason, the expectation is for both players to be looking at a suspension from the NFL. It's not clear right now just how long each player's suspension could be, but it'd be surprising if they weren't held out of at least one game in 2012.
With the Lions potentially having two players suspended for being arrested, it is possible that the franchise could face some discipline as well. Specifically, they could be forced to send some of the salary for Fairley and Leshoure to the NFL. From FOX Sports' Alex Marvez:
If both are suspended for repeat violations under the substance-abuse policy, the Lions will be required to submit to the NFL 25 percent of their respective base salaries for each game missed up to $200,000. Neither player would be paid during the suspensions.
Fairley is slated to earn $48,500 each game as part of his $824,500 base salary for 2012. Leshoure will earn $465,000, which translates to roughly $27,350 per game.
This doesn't seem like a huge potential penalty, but as noted by Anwar Richardson, if the Lions ended up facing any other potential suspensions for off-field issues, they could be looking at an increase in how much money goes toward the NFL. (The NFL, by the way, would use the collected funds to support their steroid and drug policies, Player Care Foundation and other research and development programs.)