@Sleep, no, you are quite wrong
Anyway, here is IMHO a more interesting question -
Is one justified in oing bad things when under the influence of drugs...for instance, someone may commit an assault while under the influence of a hallucinogen. They did not mean to commit the crime, and will certainly not do it again, as it was not deliberate in the first place. So are they accountable? What is the difference between drug induced insanity and birth-defect or injury induced insanity? What about emotionally induced insanity?
This is off topic, so I'll edit it out if you want @Rob