Hong Kong’s over-stretched legal system is facing an “immense” new challenge in the wake of a ruling by the United Kingdom’s top court which could potentially see the convictions of hundreds

of murderers and violent criminals in the city overturned on appeal.

Local legal experts have described as “unprecedented’’ and “dramatic” the ruling by the Supreme Court in the UK that the law “took a wrong turn’’ when it established the legal principle of “joint enterprise’’ on the basis of a Hong Kong murder case more than 30 years ago.

The ruling – handed down late last week – could pave the way for people convicted of murder or violent crime to appeal if they neither inflicted the fatal blow nor intended serious harm. It could also force the Department of Justice and law enforcement agencies to completely rethink the way they prosecute cases.

A spokeswoman for the Judiciary said it was “inappropriate” to comment, while the Department of Justice had not responded to the Post’s questions last night.

Veteran senior counsel Michael Blanchflower said the cases involved over the past 30 years could potentially run into “hundreds” and dealing with them would pose an “immense administrative task’’ for the Judiciary.

Describing the ruling as unprecedented, Blanchflower said: “The decision of the UK Supreme Court and Privy Council was unanimous. So it is a very persuasive judgment.

“Of course, it would not be binding upon Hong Kong courts, but in the circumstances where Hong Kong and the UK have applied the same cases and law on joint enterprise, I do not see a Hong Kong court refusing to follow this decision.

“The number of cases will be significant because joint enterprise was the prosecutors’ choice for charging multiple defendants who were present at the time of an offence.

“In many cases, the prosecution has relied on joint enterprise against multiple defendants: from triad-related offences, to assaults and woundings, to murder,’’ added Blanchflower, a key drafter of Hong Kong’s landmark Organised and Serious Crimes Ordinance in the 1990s.

One of Hong Kong’s leading criminal lawyers, Colin Cohen – who represented jailed property tycoon Thomas Kwok Ping-cheung and so-called “milkshake murderer” Nancy Kissel – characterised the ruling as “a dramatic change in the law’’.

“There is no doubt in my mind that in this case the ruling of the Supreme Court of England and Wales should be followed. This is a dramatic change in the law that not only has the potential to create a lot of work for the Judiciary but will also require very careful thought by the director of public prosecutions,’’ said Cohen, a senior partner in Hong Kong law firm Boase, Cohen & Collins.

Leading criminal law academic Michael Jackson, who acts as a consultant for the law firm, said the ruling had “substantial ramifications”.

“Hopefully, the Court of Final Appeal will seize the first opportunity to consider this judgment and clarify both the law in Hong Kong and the possibility of appeal,” Jackson said.

The UK Supreme Court issued its judgment after considering the case of Ameen Jogee, who was convicted of murder after his friend Mohammed Hirsi stabbed a man to death in Leicester, England, in June 2011.

The court overturned his conviction after concluding it had been secured on the grounds that he merely had foresight of the potential that the victim, Paul Fyfe, could suffer life-threatening injuries.

The Supreme Court said that because Jogee had not been in the room at the time of the killing, it had not been proven he actively assisted or encouraged the crime.

Joint enterprise liability – or alternatively parasitic accessory liability – originated in a decision of the Privy Council on appeal from Hong Kong in Chan Wing-siu v. The Queen in1985.

“In theory, the Hong Kong courts could decline to follow the Supreme Court’s ruling, since it is not legally binding here. But, given the express declaration that Chan Wing-siu, the foundation of joint enterprise liability in Hong Kong, involved a ‘wrong turning’, this would be a most surprising step,” added Jackson.

The guilty trio

The principle of joint enterprise dates back to a 1980 murder trial in British-run Hong Kong.

Chan Wing-siu, Wong Kin-shing and Tse Wai-ming were sentenced to death for killing Cheung Man-kam. The trio – all in their 20s at the time – had stormed the flat of a prostitute, Lam Pui-yin, Cheung’s wife. Two of the men confronted her husband in the kitchen while Tse stood guard over the woman. They were all armed with knives.

The two men in the kitchen stabbed the husband to death after one shouted “stab him down”. The three then fled the property together, slashing the woman as they left and shouting “stab her down too”. She was hurt but survived.

The jury found all three men guilty of murder, on the direction of the judge, and they were sentenced to death. On the formal abolition of such a penalty in 1993, their terms were commuted to life in prison.

Mr Justice Macdougall said Tse was guilty of the same crime as the “primary” killer because he could have foreseen the possibility that the primary offender might have acted as he did.

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