Legal Case Summary
R v Cato [1976] 1 WLR 110
Causation and whether consent of victim to injections is relevant; requirements of unlawful and malicious administration of “noxious thing” under s. 23 of the Offences against the Person Act 1861
Facts
Mr Cato and the victim prepared their own syringes and then injected each other with heroin. The victim died. Mr Cato was convicted of manslaughter and administering a noxious thing contrary to s. 23 of the Offences Against the Person Act 1861. He appealed against his conviction.
Issues
The jury was asked to decide whether the injection caused, contributed to or accelerated the victim’s death. The judge did not provide the direction that cause or contribution should be substantial, and advised the jury that the victim’s consent to the heroin injection was irrelevant to the consideration of whether Mr Cato was reckless or grossly negligent (i.e. whether he committed manslaughter). Mr Cato argued that the trial judge had thus misdirected the jury. He also claimed that heroin was not a “noxious” thing and that “malicious” administration under s. 23 OAPA 1861 had not occurred – i.e. the act of injection was not unlawful.
Decision / Outcome
The injection of heroin had to be the cause of death in order to find that manslaughter had taken place. Even though no express directions were given about the necessity of “substantial” cause of death, it must have been clear to the jury that more than a de minimis contribution was required. Secondly, the victim’s consent might be relevant to the finding of recklessness or gross negligence but consent in itself is not a defence to manslaughter. The jury was thus not misdirected. Thirdly, as Mr Cato had unlawfully taken heroin into his possession in order to inject the victim with it, the act of injection was itself unlawful in relation to the charge of manslaughter. Finally, heroin is a potentially harmful substance and thus a “noxious” thing for the purposes of s. 23 OAPA 1861; since the act of administration was deliberate and direct, there is no need to find “maliciousness”.
Updated 20 March 2026
This case summary accurately reflects the decision in R v Cato [1976] 1 WLR 110. The core principles established by the case — concerning causation in manslaughter, the irrelevance of the victim’s consent as a defence to manslaughter, the unlawfulness of the act of injection, and the interpretation of ‘noxious thing’ and ‘malicious’ administration under s. 23 of the Offences Against the Person Act 1861 — remain good law.
Readers should be aware of subsequent developments in related areas. The approach to unlawful act manslaughter, including the requirement that the unlawful act be dangerous, was further considered in cases such as R v Kennedy (No 2) [2007] UKHL 38, where the House of Lords held that a person who freely and voluntarily self-administers a drug cannot be regarded as the victim of another’s unlawful act for the purposes of manslaughter. Kennedy does not overrule Cato but significantly limits its application: the key factual distinction is that in Cato the defendant himself injected the victim, whereas in Kennedy the defendant merely prepared and handed over a syringe which the victim self-administered. Students should read these two cases together to understand the current law on causation and manslaughter in drug injection cases. Section 23 of the Offences Against the Person Act 1861 remains in force and unamended in the relevant respects.
