Seterusnya, dalam kes PP v. Mohd Rozani Yahaya [2025] 2 CLJ 21, Panel Mahkamah Persekutuan melalui penghakiman oleh Zabariah Mohd Yusof, HMP (pada masa tersebut) telah dengan panjang lebar menerangkan prinsip undang-undang berhubung pembelaan tidak waras serta perbezaan antara legal insanity dan medical insanity, sebagaimana berikut: "The law on the defence of insanity - Medical Insanity and legal insanity: [37] Within the labyrinth of mental health and the legal system, stood the concepts of medical and legal insanity, which are distinct but interconnected in their realm. Undeniably, both the terms appear to share some common traits, as they deal with conditions affecting the human mind. However, each term serves different purposes and has varying implications for individuals in areas of medicine and in court proceedings. [38] It is important to be borne in mind of the distinct nature of these two terms, more so when the defence of insanity is raised in criminal proceedings, as it affect the ultimate order given by the court against the accused. [39] The term "medical insanity" refers to a disorder of the mind which covers a whole range of mental health conditions which may impair one's cognitive or emotional functions. It encompasses disorders such as anxiety, depression and other psychiatric conditions that may require medical attention and treatment. These conditions, however do not necessarily render one as legally insane under section 84 of the Penal Code, so as to accord a complete defence in criminal law when an offence has been committed. [40] In medical insanity, the emphasis is on one's mental health and well-being or psychological disorder, with the primary goal being the diagnosis, treatment and management of the mental disorder. It is a medical diagnosis based on one's mental health condition. Persons experiencing medical insanity may still possess the capability to make informed decisions and can lead a life of normalcy with the appropriate medical intervention. Medical insanity is diagnosed by healthcare professionals premised on medical criteria and considerations, symptoms and the impact of mental illness on the individual's daily functions. The consequences of a finding of medical insanity will primarily lead to medical treatment, therapy and other interventions aimed at managing and improving the individual's mental health. Every person who is mentally ill is not, ipso facto, exempted from criminal responsibility. [41] Whereas, legal insanity involves a distinct set of criteria and considerations within the framework of the legal system. Unlike medical insanity, which involves a question of mental health only, legal insanity goes beyond mental health and pertains to one's legal capacity and responsibility for their actions. It involves a legal determination that a person, due to a severe mental disorder, is not criminally responsible for their actions. It is a legal status that affects the person's accountability to his actions in a court of law. This accords the rationale of legal insanity being a recognised defence in criminal law, as it implies that, at the time when committing an offence, the accused was found to be in a state of not understanding the nature and consequences of his/her actions. Legal insanity is determined by legal standards, which may vary by jurisdiction. It entails assessments by mental health experts and legal professionals to analyse and evaluate the accused's mental state at the time of the alleged offence committed. The consequences of legal insanity may result in the accused being declared not criminally responsible or being committed to a psychiatric institution instead of facing traditional criminal penalties. [42] For the accused, to succeed on the defence of legal insanity, the accused must establish, often through psychiatric or psychological evaluations, that he/ she was not in control of his/her reasoning during the commission of the offence. This defence is anchored in section 84 of the Penal Code, which outlines the conditions under which an accused can be considered legally insane. [43] The burden of proof for medical and legal insanity also differs. In legal insanity, the onus lies with the accused to prove his/her mental state at the time when the offence was committed pursuant to section 105 of the Evidence Act 1950. This burden though significant is not as onerous as the prosecution to prove the accused's guilt. It is on a balance of probabilities and not merely to cast a reasonable doubt in the prosecution's case (see Rajagopal v. PP [1976] CLJU 122 and Goh Yoke v. PP [1969] CLJU 48) [44] To establish legal insanity, the accused must present a prima facie case, supported by reasonable materials. This involves presenting evidence of the accused's conduct, before, during and immediately after the commission of the alleged offence, corroborated with the relevant medical documentation. The purpose is to convince the court that due to the accused's mental capacity, the accused should be exempt from full criminal responsibility."