Cal. Fam. Code § 783

If a married person is injured by the negligent or wrongful act or omission of a person other than the married person’s spouse, the fact that the negligent or wrongful act or omission of the spouse of the injured person was a concurring cause of the injury is not a defense in an action brought by the injured person to recover damages for the injury except in cases where the concurring negligent or wrongful act or omission would be a defense if the marriage did not exist.