What is the test for evidence of voluntary intoxication in a murder case?

voluntarily intoxicated. Initially enacted in 1872, [former] section 22 [now renumbered section 29.4] sets forth the general principle in this state that a criminal act is not rendered less criminal because a person commits the act in a state of voluntary intoxication. [Fn. omitted.] Evidence of voluntary intoxication is not allowed to negate the capacity to form any mental states for the crimes charged. However, such evidence is admissible on the issue of whether the defendant actually formed a required specific intent or, with respect to a charge of murder, whether the defendant premeditated, deliberated, or harbored express malice aforethought. (Id., subd. (b).)" (People v. Timms, supra, 151 Cal.App.4th at pp. 1296-1297.)