QUESTION OF LAW RESERVED (NO 1 OF 2021)

In *Question of Law Reserved (No 1 of 2021)*, the Supreme Court of South Australia considered questions of law reserved concerning the defence of mental impairment in criminal proceedings. The defendant, William Robert Delany, faced charges including murder, aggravated causing harm with intent to cause harm, and assault, stemming from events on 19 August 2019. The defendant had a history of diagnosed schizophreniform psychosis and paranoid schizophrenia, for which he was receiving treatment. In the period leading up to the alleged offending, the defendant consumed methylamphetamine and cannabis.

The court was required to determine the application of Part 8A of the *Criminal Law Consolidation Act 1935* (SA), specifically concerning mental impairment and self-induced intoxication. The central legal issues revolved around whether intoxication, as defined by the Act, could constitute a "mental impairment" for the purposes of the defence, and the interpretation of the phrase "substantially caused by" in relation to the relationship between self-induced intoxication and mental impairment. The court also considered the role of expert evidence in determining these factual issues.

The court held that "intoxication" as defined in s 269A(1) of the Act cannot be a "mental impairment" for the purposes of Part 8A, particularly s 269C. Regarding the causation element, the court clarified that the term "substantially caused by" in s 269C(2) does not require self-induced intoxication to be the primary cause of the mental impairment, acknowledging that multiple causes of mental impairment can exist. Furthermore, the court affirmed that the issues raised by s 269C are questions of fact to be determined by the court in each case, based on admissible expert opinion evidence but not governed by it, with the ultimate determination resting with the court.

The questions of law reserved were answered as follows: Question 1 was answered "No," Question 2 was answered "No," and Question 3 was answered "Yes."