DALLAS — Johnny Manziel has been suspended for the first four games of next season for violating the NFL’s substance-abuse policy, and the free agent quarterback could face further discipline over his domestic violence case if he signs with another team.

The suspension announced Thursday is not related to the league’s domestic violence policy, but Manziel would be subject to standards that were toughened two years ago if he signs with another team. The 23-year-old Manziel, released by Cleveland in March, faces a misdemeanor assault charge in Dallas involving former girlfriend Colleen Crowley.