Murder is an offence under the common law of England and Wales. It is considered the most serious form of homicide, in which one person kills another with the intention to unlawfully cause either death or serious injury. The element of intentionality was originally termed malice aforethought although it required neither malice nor premeditation.
Because murder is generally defined in law as an intent to cause serious harm or injury (alone or with others), combined with a death arising from that intention, there are certain circumstances where a death will be treated as murder even if the defendant did not wish to kill the actual victim. This is called "transferred malice", and arises in two common cases: -
The unlawful killing of a reasonable person in being under the King (or Queen's) peace with malice aforethought express or implied.
The definition of the actus reus (Latin for "wrongful act") of murder most usually cited is that by Coke:
The latter clause (known as the 'year and a day rule') was abolished in 1996 (see below).
A further historic rule, the felony murder rule, was abolished in the Homicide Act 1957. Until abolition, the effect of this rule had been to create murder offences in two cases: when manslaughter occurs during the course of a crime it could in certain cases be automatically reclassified by law as murder, and that any deaths resulting from acts of a criminal during the crime could cause culpability as murder on the part of all his or her fellow criminals. The effect of this rule are partly retained despite abolition, since intent to kill is not necessary - intent (including common intent) to cause serious injury is sufficient for murder if death results.