While it might be an exceedingly rare defence to certain sections of the criminal code, the Supreme Court of Canada recently ruled that the defence of automatism in cases of extreme intoxication remains valid, and that laws prohibiting the defence are unconstitutional.
Charter Subsections 7 and 11(d) were found to have been breached with s. 33.1 of the Criminal Code. The constitutional challenge now means that automatism in the case of intoxication is a still valid, albeit exceedingly rare.
One of the reasons for automatism being so rare of a defence is that it must essentially be accompanied with a huge amount of psychiatric and medical evidence weighed on a balance of probability.
"This is not a drunkenness case. B consumed a drug which, taken in combination with alcohol, provoked psychotic, delusional and involuntary conduct," wrote Justice Nicholas Kasirer in R. v. Brown
This legal case along with R. V. Sullivan were heard together by Canada's top court. The ruling shouldn't be misinterpreted as excusing the unexpected effects of combining psychotropic substances with one another. The court made it clear in these decisions that a "regime of absolute liability" in the case of intoxication actually undermines constitutional law to such an extent that it must be stricken down despite the extreme rarity of such defences.
The relevant section of the Criminal Code 33.1(1) reads the following, for when defence not available: "It is not a defence to an offence referred to in subsection (3) that the accused, by reason of self-induced intoxication, lacked the general intent or the voluntariness required to commit the offence, where the accused departed markedly from the standard of care as described in subsection (2).
This ruling only concerns defences where intoxication produces a psychotic state akin to automatism, it doesn't affect criminal liability for offences when intoxication doesn't meet a threshold associated with automatism.