Section 1 of the Act abolished constructive malice except where the intention implicit in the other crime was an intention to kill or to do grievous bodily harm.

It is based on the doctrine of constructive malice, whereby the malicious intent inherent in the commission of a crime is considered to apply to the consequences of that crime.

The doctrine of felony murder or "constructive malice" meant that a charge of manslaughter was not an option, as the "malicious intent" of the armed robbery was transferred to the shooting.

Constructive malice was the doctrine that malice aforethought, the mental element for murder, could be attributed to the defendant if death was caused during the commission of another felony (such as robbery or burglary).

The judges there made reference to the abolition under the Homicide Act 1957 of constructive malice (causing death whilst committing a felony or resisting arrest), believing the rule for grievous bodily harm to be a hang-over of the old system.

Although the marginal note to the section purports to abolish the doctrine of "constructive malice", it did not abolish the concept of felony, the rules relating to the arrest of felons or the general rules specifying the test for the mental element which the juries were to apply.

It was enacted as a partial reform of the common law offence of murder in English law by abolishing the doctrine of constructive malice (except in limited circumstances), reforming the partial defence of provocation, and by introducing the partial defences of diminished responsibility and suicide pact.