Murder: what the prosecution must prove, defences and sentence
Murder is the unlawful killing of a human being under the King's peace with intent to kill or to cause grievous bodily harm. It is tried only in the Crown Court and carries a mandatory life sentence, with the judge setting a minimum term.
The offence
Murder is a common-law offence, not defined in statute. The prosecution must prove:
- An unlawful killing. The defendant's act (or, where there was a legal duty to act, omission) caused the death of a living human being, and the killing was not lawful.
- Causation. The defendant's conduct must be a substantial and operating cause of death, though not necessarily the only or main cause (R v Pagett (1983)). There is no time limit between injury and death, but the Attorney General's consent is needed if death came more than 3 years after the injury (Law Reform (Year and a Day Rule) Act 1996).
- Intent. An intention to kill, or to cause grievous bodily harm (really serious harm) (R v Vickers [1957]; R v Cunningham [1982]). Motive is not required. Where that was not the defendant's purpose, a jury may find intent only if death or serious harm was a virtual certainty and the defendant appreciated that (R v Woollin [1999]). Without intent, the killing may still be manslaughter.
Defences
- Self-defence or prevention of crime is a complete defence (Criminal Justice and Immigration Act 2008 s.76; see Self-defence and reasonable force). Duress is not a defence to murder (R v Howe [1987]).
- Partial defences reduce murder to manslaughter (see Manslaughter: voluntary and involuntary): diminished responsibility (Homicide Act 1957 s.2, as amended), loss of control (Coroners and Justice Act 2009 ss.54 to 55) and suicide pact (Homicide Act 1957 s.4). The defence must prove diminished responsibility on the balance of probabilities; once there is sufficient evidence of loss of control, the prosecution must disprove it.
Court and sentence
Murder is tried only in the Crown Court. The sentence is mandatory life (Sentencing Act 2020 s.322 for those aged 21 or over; equivalent mandatory sentences apply to younger offenders). The judge sets the minimum term before parole can be considered, using Schedule 21: a whole life order in the most serious cases (21 and over), then starting points of 30, 25 (a knife or weapon taken to the scene and used) or 15 years. Lower, age-banded starting points apply to under-18s. Aggravating factors added since 2024 include coercive control, strangulation and a killing connected with the end of a relationship.
Reform
The Law Commission's 2026 proposals for first and second degree murder are not law.
In practice
Advice before any interview is essential: what is said, and not said, can decide whether a partial defence is available later. Others involved may face murder charges as secondary parties (see Joint enterprise and secondary liability).
Authorities: Common law (murder); R v Pagett (1983) 76 Cr App R 279; R v Vickers [1957] 2 QB 664; R v Cunningham [1982] AC 566; R v Woollin [1999] 1 AC 82; R v Howe [1987] AC 417; Law Reform (Year and a Day Rule) Act 1996 s.2; Criminal Justice and Immigration Act 2008 s.76; Homicide Act 1957 ss.2 and 4; Coroners and Justice Act 2009 ss.52, 54 to 55; Sentencing Act 2020 s.322 and Sch.21 (as amended by SI 2024/137 and SI 2025/1071); Law Commission, Homicide Offences consultation paper (June 2026)