Prosecutors said there was "insufficient evidence" to prove the case "beyond a reasonable doubt," and made their determination after reviewing the Los Angeles County Sheriff's investigation and re-interviewing witnesses.
The actor told authorities that his son, Griffin, picked up a fireplace poker and started swinging it. The younger O'Neal grazed him four or five times and "aimed at my head, I ducked, he hit his own girlfriend in the head," O'Neal said.
The actor said he fired a "warning shot" intended to scare his 42-year-old son, who came at him with a fireplace poker. He said his son struck Berry, 22, with the poker during the fight.
The elder O'Neal was nominated for an Oscar for the 1970 movie "Love Story."