In R. v. Porritt [1961] 1 W.L.R. 1372; 45 Cr.App.R. 348 the accused had been convicted of the capital murder of his stepfather. His defence was that he fired the fatal shot in an attempt to protect the deceased from two members of a rival gang, the Copleys, one of whom was holding a knife at his throat. He further pleaded that he was repelling an armed invasion of his home by the Copleys.

The accused clearly had no desire whatever to harm his stepfather, who seems to have been an active member of the same gang as the accused. He was however prima facie guilty of murder should the prosecution establish his intent by shooting to cause death or grievous bodily harm to the Copleys, under the doctrine of transferred malice, whereby the accused is legally responsible for intended consequences even though they are visited upon an unintended victim: Hopwood (1913) 8 Cr.App.R. 143.

Defences are also transferred with the malice; Conner (1836) 7 C. & P. 438, and the prosecution conceded that the homicide was justifiable if done in the honest belief that it was necessary to preserve the life of his stepfather or to protect his home from invasion. The concession was in generous terms, as the authorities require not merely honest belief on the part of the accused, but reasonable grounds for this belief: Rose (1884) 15 Cox 540. The defence that the Copleys were seeking to dispossess the Porritts carried the matter little further, except that it has been held that there is no duty to retreat in such a case: Hussey (1924) 18 Cr.App.R. 160.