R v Chan Wing-Siu  AC 168
Parasitic Accessory Liability, foresight and intent
On May 31st 1980, the Appellant along with two others, in Kowloon, entered the premises of the two victims (a husband and wife) in order to collect a debt. Two of the three assailants knew that the others carried knives. The wife opened the door and all three men pushed inside. They drew knives, one (by the name of Tse) was left to guard the wife while the other two fought with the husband. The husband was stabbed and later died, while the two who assailed him also suffered substantial injuries in the struggle. The wife was not able to see which of the two assailants stabbed her husband. As they were leaving, one of them also slashed her across the head, but she could not see who it was. The defendants Chan and Tse denied being involved with the stabbing of the husband and Wong admitted to stabbing him in self-defence after he had been attacked with knives. All three defendants asserted that the husband attacked them first. The defendants were charged under Chapter 212, Section 17 of the Offences Against the Person Ordinance (Hong Kong) and convicted of murder.
Whether foresight of the possibility that the principal may commit a crime which went beyond the plan of the initial joint venture was sufficient mens rea to justify a conviction under accessory liability.
It was sufficient for a conviction under the principle of joint enterprise/parasitic accessory liability that a defendant foresees that the principal may commit an offence which goes beyond the plan, even if he does not intend that the offence be carried out. Foresight in this case is sufficient intent. Overturned by R v Jogee  UKSC 8.