How does evidence of voluntary intoxication reduce a defendant's first degree murder to second degree murder?

Evidence of voluntary intoxication can be used to negate evidence of premeditation and deliberation. ( 29.4, subd. (b).) Thus, evidence of intoxication can operate to reduce a first degree murder to second degree murder. ( People v. Turk (2008) 164 Cal.App.4th 1361, 1376-1377, 80 Cal.Rptr.3d 473.) The trial court instructed the jury on how voluntary intoxication reduces first degree murder to second degree murder. During closing argument, defendant's trial counsel argued that defendant consumed "about 30 beers" and marijuana within approximately six hours. Defense counsel asserted defendant did not plan the shooting because he was intoxicated.