Bui v The Queen

In *Bui v The Queen*, the appellant, Bui, appealed to the High Court of Australia against his conviction for murder. The central dispute concerned the admissibility of certain evidence obtained during a police investigation and the subsequent application of the *Criminal Code Act 1899* (Qld) in relation to the appellant's mental state at the time of the offence.

The High Court was required to determine whether the evidence obtained by police, including statements made by the appellant, was unlawfully obtained and therefore inadmissible under s 138 of the *Evidence Act 1977* (Qld). Furthermore, the Court had to consider whether the appellant's mental impairment, as evidenced by expert testimony, constituted a defence to the charge of murder under the provisions of the *Criminal Code*. Specifically, the Court examined the elements of the offence of murder and the defence of diminished responsibility.

Kiefel and Gageler JJ reasoned that the evidence in question was not unlawfully obtained, as the police actions, while potentially intrusive, did not contravene any specific legal prohibition at the time. Regarding the mental state, their Honours held that the evidence of the appellant's mental impairment did not meet the threshold required to establish a defence of diminished responsibility under the *Criminal Code*. The legal principle applied was that the defence requires proof that the impairment substantially impaired the appellant's capacity to control his actions, a standard not met by the presented evidence.

The appeal was dismissed, with the High Court affirming the conviction for murder.