Common law
The common lawso named because it was "common" to all the king's courts across Englandoriginated in the practices of the courts of the English kings in the centuries following the Norman Conquest in 1066. The British Empire spread the English legal system to its historical colonies, many of which retain the common law system today. These "common law systems" are legal systems that give great precedential weight to common law, and to the style of reasoning inherited from the English legal system.
South African criminal law
Common Purpose: Active Association
The common-purpose rule originated in English law and was introduced into South Africa via the Native Territories’ Penal Code. The much-publicised murder conviction of the “Sharpeville Six” in terms of the common-purpose doctrine, in S v Safatsa 1988 (1) SA 868 (A), highlighted the significance of the common-purpose doctrine in the context of the administration of criminal justice in South Africa. The controversial imposition of the death penalty on the Six also played a significant role in strengthening the call for the abolition or reassessment of the death penalty in South Africa.
Evidence of the specific participation of the Sharpeville Six in the murder of the deputy-mayor of Lekoa was meagre, aside from the fact that they had joined the crowd of about a hundred persons that attacked the deceased’s house in Sharpeville. It was not possible to determine which members of the mob had been personally responsible for killing the mayor. 
Nevertheless, there was some evidence to implicate the Six in the subsequent killing of the deceased. He was killed by stoning and burning perpetrated by some members of the crowd, but it was not possible to determine which specific members had participated directly in the killing.
Accused number 1 had grabbed hold of the deceased, wrestled with him for possession of his pistol, and thrown the first stone at the deceased, which felled him.
Accused number 2 had thrown stones at the deceased and at his house. After the deceased’s house had been set alight, accused number 2 had thrown a stone at the deceased which had struck him on his back.
Accused number 3 had grabbed the deceased, wrestled with him for possession of his pistol, and succeeded in dispossessing him of the weapon.
Accused number 4 was part of the crowd which converged on the deceased’s house; she had shouted repeated exhortations to the crowd to kill the deceased (since the deceased was shooting at them) and had slapped a woman who had remonstrated with the crowd not to burn the deceased.
Accused numbers 5 and 6 had been part of the vanguard of the crowd which had converged on the deceased’s house and stoned it, but they were not seen to have thrown any stones themselves, and were ultimately acquitted on the basis that there was insufficient evidence to conclude that they shared the requisite intent to kill at the relevant time.
Accused number 7 had made petrol bombs, set the deceased’s house alight, and pushed the deceased’s car into the street and set it alight.
Accused number 8 had also made petrol bombs and handed them out with instructions, had commanded the mob to set the deceased’s house on fire, and had assisted in pushing the car into the street.
The Appellate Division, in a unanimous judgment, approved the conviction of the Six on the basis of the doctrine of common purpose. The court pointed out that the intention of each participant must be considered, together with the question of whether or not each had the requisite dolus in respect of the death. The court traced the historical development of the doctrine, and found that “it would constitute a drastic departure from a firmly established practice to hold now that a party to a common purpose cannot be convicted of murder unless a causal connection is proved between his conduct and the death of the deceased. I can see no good reason for warranting such a departure.”
In S v Mgedezi 1989 (1) SA 687 (A), the Appellate Division drew a distinction between common-purpose liability
• where there is a prior agreement, expressed or implied, to commit a crime (the mandate situation); and
• where there is no such prior agreement.
In the latter situation, certain additional requirements have to be satisfied before the principle of imputation, which is the characteristic of common-purpose liability, can arise.
In S v Mgedezi, the court held that, in the absence of proof of a prior agreement, an accused who was not shown to have contributed causally to the killing or wounding of the victims could be held liable for those events on the basis of Safatsa only if certain prerequisites were satisfied: 
• he must have been present at the scene where the violence was being committed;
• he must have been aware of the assault on the victims;
• he must have intended to make common cause with those who were actually perpetrating the assault;
• he must have manifested his sharing of a common purpose with the perpetrators by himself performing some act of association with the conduct of the others; and
• there must be the requisite mens rea. In respect, therefore, of the killing of the deceased, he must have intended them to be killed, or must have foreseen the possibility of their being killed and performed his own act of association with recklessness as to whether or not death was to ensue.
In S v Thebus 2003 (6) SA 505 (CC), the Constitutional Court considered the active-association form of common purpose. The court held that, in its then-current form, the doctrine violated a number of constitutional rights. The formulation in Mgedezi, however, passed constitutional muster.
It can no longer be said, then, that common-purpose doctrine is part of the old order, since it has been ratified as constitutional in the new one.
Thebus has been criticised, though, for having dispensed with the causation element, and for its infringement on the presumption of innocence and the requirement that the prosecution prove each element of the crime. 
See Burchell 580-588; Snyman 263-272.