"If he successfully completes the program, which is at least a year but could be longer, his criminal convictions in two separate cases for drug possession will be dismissed. If he fails, he could face up to four years in state prison," said Jane Robison, the district attorney's press secretary.
O'Neal, whose mother is actress Farrah Fawcett, pleaded no contest this month to a felony charge of methamphetamine possession after drugs were found in a raid on his 67-year-old father's Malibu home in September.
He was on probation at the time of the raid following a guilty plea in June 2008 for possession of heroine and methamphetamines, and driving under the influence.
He was arrested for drug possession again on April 5 outside a prison after visiting a friend. He is due in court May 22 for a preliminary hearing in that case.
Ryan O'Neal, who received an Oscar nomination for Love Story in 1971 and also starred in Stanley Kubrick's "Barry Lyndon," was sentenced in January to 18 months in a drug rehabilitation program.
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