Prosecutors say Leal was driving under the influence of alcohol shortly before 5 a.m. in December 2008. He drove for several miles on the wrong side of Interstate 5 in Anaheim near Disney Way before crashing into an oncoming Toyota Corolla, killing a passenger in that car, 29-year-old Rebecca Moon.
The driver of the Toyota was injured but survived the crash.
Leal had two prior convictions for driving under the influence and was driving on a suspended license at the time of the accident.
He faces a maximum sentence of 15 years to life in state prison.
Leal is scheduled to be sentenced November 5.