Los Angeles District Attorney Sean Carney told a judge the Saving Private Ryan star tested positive for drugs on Jan. 23, violating his probation.
Carney claims Sizemore was ejected from a drug treatment program on Tuesday.
Superior Court Judge T.K. Herman called a hearing after the latest accusations, to determine if Sizemore had violated his probation, which stems from a conviction for methamphetamine possession. If it is revoked, the 44-year-old faces 16 months in prison.
But the actor insists he was only talking with the person he is alleged to have rowed with, claiming the man would testify on his behalf.
Sizemore's probation was revoked for the first time last July when he admitted using a fake penis to supply a drug test. He also failed to attend a compulsory drug test every three days.
His probation was reinstated in October when Superior Court Judge Paula Mabrey asserted the actor was making "remarkable" progress.
Article Copyright World Entertainment News Network All Rights Reserved.