Does a defendant have diminished capacity because of drug abuse at the time of the incident?

"Defendant testified in his defense and presented expert witnesses who suggested he may have suffered from diminished capacity because of drug [17 Cal.4th 894] abuse at the time of the incident. Defendant admitted he had suffered a 1970 felony conviction in Florida for 'burglary.' He detailed his extensive drug abuse history and claimed to have been under the influence of methamphetamines on the night in question and that he remembered nothing of the events in question. In rebuttal, the People established that defendant's blood sample, taken shortly after his arrest, showed no presence of drugs and specifically, the test for methamphetamine was negative. Moreover, numerous officers who dealt with defendant in the four to five hours after his arrest testified that although he 'stank like a pig' he behaved normally and did not appear to be under the influence of any drug." (People v. Brown (1988) 46 Cal.3d 432, 440-441, 250 Cal.Rptr. 604, 758 P.2d 1135.)