Judge Richard Toohey's ruling was separate from the jury deliberations that are ongoing.
The 23-year-old Gallo has been charged with three counts of second-degree murder. Prosecutors said Gallo was drunk behind the wheel when he ran a red light on April 9, 2009, in Fullerton and crashed into a car carrying the victims.
22-year-old Adenhart, 20-year-old Courtney Stewart and 25-year-old Henry Pearson died in the accident. Another friend suffered critical injuries. Gallo has pleaded not guilty.
If convicted, he faces a maximum sentence of 54 years and eight months to life.
City News Service contributed to this report.
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