According to section 2(1) of the Homicide Act 1957 the defence of diminished responsibility is available where the defendant is charged with murder and he was suffering from abnormality of mind which “substantially impaired his mental responsibility” for the killing. The question for the House of Lords to resolve in Dietschmann [2003] UKHL 10, [2003] 2 W.L.R. 613 was how this defence should operate where the defendant was suffering from a mental abnormality, in that case arising from a grief reaction following the death of his girlfriend (who also happened to be his aunt), but where he was also heavily intoxicated at the time. Over the years a two-stage test has been developed by the courts to deal with such cases: see Egan [1992] 4 All E.R. 470.