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Doctrine of “basic joint enterprise” not applicable to unlawful assembly and riot, Court of Final Appeal rules

On 4 November 2021, the Court of Final Appeal handed down its landmark decision which clarifies the approach for determining principal liability for unlawful assembly and riot. Significantly, the Court overturned the Court of Appeal’s opinion in holding that the doctrine of basic joint enterprise is not applicable to the two offences.

Hectar Pun SC and Anson Wong Yu Yat acted for the successful Appellant in Secretary for Justice v Tong Wai Hung (FACC 7/2021), while Jason Ko (led by Gladys Li SC, with Lawrence Lau and Kin Lau) acted for the Appellant in HKSAR v Lo Kin Man (FACC 6/2021), the two appeals being heard together.


In FACC 6/2021, the appellant Lo Kin Man (“Lo”) was convicted of riot after jury trial ([2018] HKCFI 1329) in relation to the Mongkok public disorder in the Lunar New Year of 2016. His application for leave to appeal to the Court of Appeal was refused ([2020] HKCA 275). The Appeal Committee of the Court of Final Appeal (“CFA”) granted leave to appeal on 6 questions of great and general importance and 1 ground of substantial and grave injustice ([2021] HKCFA 17).

In FACC 7/2021, Tong Wai Hung (“Tong”) was charged alongside two other defendants with riot in connection with the widespread social unrest in Hong Kong in 2019. Following his acquittal in the District Court ([2020] HKDC 588), the Secretary of Justice referred two questions of law to the Court of Appeal for its opinion pursuant to section 81D of the Criminal Procedure Ordinance (Cap. 221).

In its opinion ([2021] HKCA 404), the Court of Appeal (Poon CJHC, Macrae VP and A Pang J) held that: (1) the common law doctrine of joint enterprise is applicable to the offences of unlawful assembly and riot; and (2) for the offences of unlawful assembly and riot, a defendant’s presence at the scene is not necessary for criminal liability under the common law doctrine of joint enterprise. The Court of Appeal granted certification on 2 questions of law ([2021] HKCA 807) and Tong obtained leave to appeal to the CFA.

The two appeals, which raised overlapping issues, were heard together by the CFA.

Issue: whether joint enterprise doctrine applies to unlawful assembly and riot 

Since the common law has, as explained in HKSAR v Chan Kam Shing (2016) 19 HKCFAR 640, developed two forms of the joint enterprise doctrine – the basic form and the extended form, the CFA addressed the applicability of each form separately.

Basic Joint Enterprise

Suppose a group of people agree to carry out and then execute a planned crime, e.g., murder. The doctrine of basic joint enterprise (“BJE”) makes all participants in this criminal joint enterprise guilty as principals, whoever the actual perpetrator(s) of the actus reus (such as the striking of the fatal blow) might have been.

In the context of an unlawful assembly or riot, the BJE doctrine – if applicable – dictates that a defendant who was absent and did not take part in the unlawful assembly or riot together with others so assembled can still be found guilty as a principal offender.

The CFA held that, on their true construction, ss. 18 and 19 POO leave no room for operation of the common law doctrine in its BJE form because the statutory language renders that doctrine otiose and its application would give rise to duplication and possible confusion regarding the central actus reus element of “taking part” in the criminal assembly:

• In summary, an unlawful assembly is constituted when 3 or more persons assembled together conduct themselves in a disorderly manner that is intended or likely to cause a reasonable fear that they will commit a breach of the peace (s. 18(1) POO). Any person who takes part in an unlawful assembly shall be guilty of the offence of unlawful assembly (s. 18(3) POO).

• Under s. 19 POO, when any person taking part in an unlawful assembly as defined by
18(1) POO commits a breach of the peace, the assembly is a riot and the persons assembled are riotously assembled. Section 18(2) provides that any person who takes part in a riot shall be guilty of the offence of riot.

• In both offences, the centrally important actus reus element is “taking part”. Hence, a person who was absent from the scene cannot be liable as a principal offender:

The Ordinance defines participatory offences requiring a defendant not just to “take part”, but to do so as part of an “assembly”, as a person “assembled together” with others taking part. Thus, its language imports a requirement of presence at the scene before one can be held guilty as a principal offender. Such a statutory requirement cannot be displaced by the common law BJE doctrine.’ (para. 65, Judgment)

• Even in cases where the defendant is present at the scene, the BJE doctrine is inapplicable, being otiose and liable to cause confusion, since the actus reus of each of the statutory offences already involves “taking part” with others assembled together (para. 109(g), Judgment).

Extended Joint Enterprise

As regards the extended form of the joint enterprise doctrine (“EJE”), the CFA ruled that in given circumstances, it may operate to fix participants in an unlawful assembly or riot with liability for more serious offences committed in executing their joint plan.

The EJE doctrine addresses the situation where a group of defendants (say X, Y and Z) agree on a joint criminal enterprise, and in the course of carrying out the agreed plan (e.g., burglary), one of them (say X) commits a more serious offence, such as murder. The common law (as applied in Hong Kong) holds that Y and Z are equally guilty of X’s crime on the basis of EJE if it is proved that X’s commission of the further offence was foreseen by them as a possible incident of the execution of their planned joint enterprise.

The CFA held that the EJE form of the doctrine may be applicable if certain participants in the unlawful assembly or riot can be proved to have foreseen commission by one or more of their number of a more serious offence as a possible incident of the execution of their planned joint participation in the unlawful assembly or riot (para. 63(c), Judgment).

What constitutes “taking part” in an unlawful assembly or riot

Presence at the scene in itself is not enough to constitute “taking part” or aiding and abetting (para. 81, Judgment). 

The CFA clarified that “taking part” is a broad expression which embraces not only conduct prohibited by the statutory provisions, but also conduct which facilitates, assists, or encourages the performance of such conduct by others participating in the assembly. A defendant who engages in such conduct may attract liability either as a principal offender or as an aider and abettor (para. 14). Persons convicted as accessories or for inchoate crimes are punishable to a like extent as principal offenders (para. 70).

Whether a defendant has done enough to constitute “taking part”, especially if by way of encouragement, is a matter of fact and degree, taking all the circumstances into account (para. 85).

In deciding whether a defendant was present at the scene, the court should take into account the possible fluidity of the criminal assembly and the communications maintained by participants with each other in ascertaining the time, place and scope of the assembly in question (para. 109(e), Judgment).

Potential liability of persons absent from the scene

Even though the BJE doctrine is held to be inapplicable, the CFA stressed that persons absent from the scene may still be subject to secondary or inchoate liability for unlawful assembly or riot (para. 63(d), Judgment).

For instance, the “mastermind” who remotely oversees the situation and gives commands or directions to the participants on the ground would be guilty of incitement or as counsellor and procurer of the criminal assembly (para. 69, Judgment).

Participatory intent and common purpose

The CFA held that unlawful assembly and riot are both “participatory offences” which require “participatory intent”.

In respect of unlawful assembly, the defendant must intend to take part in the unlawful assembly, “being aware of the related conduct of other participants and intending, while assembled together with them, to engage in or act in furtherance of the prohibited conduct”, i.e. the “participatory intent” (para. 17, Judgment). To be guilty as a principal offender, the defendant must be present as part of the assembly together with other participants (para 18, Judgment).

In respect of riot, the defendant’s conduct amounting to “taking part” must involve acts in furtherance of the riot. It must involve committing breaches of the peace or doing acts facilitating, assisting or encouraging breaches of the peace by others. The defendant must have a participatory intent, “intending to take part in the riot by committing, or acting in furtherance of, breaches of the peace together with other participants engaged in riotous activities” (para. 22, Judgment) and “being aware of their related prohibited conduct” (para. 50, Judgment). Liability for the offence of riot as a principal therefore requires the defendant to be present and acting with the others riotously assembled (para. 23, Judgment).

Lo argued that the prosecution needs to prove not only the defendant’s intent to participate in the assembly, but an “extraneous common purpose” which the assembled persons jointly intended to pursue, such as to wreck a dinner or cause a work stoppage.

Having observed that the common law authorities were “in some disarray” (para. 29, Judgment), the CFA held that ss. 18 and 19 POO replaced the common law and eliminated any requirement for proof of a “common purpose” (para. 39, Judgment). It is preferable not to refer to “common purpose”, but to recognise instead the requirement of participatory intent, which reflects the participatory nature of the two offences (para. 40, Judgment).

Issue: whether indictment must mention other unnamed riot participants

In respect of an indictment for unlawful assembly or riot, the CFA affirmed that it is common and good practice to add the allegation that the defendant’s participation was also “with persons unknown” or “with persons not before the court”. It was a material irregularity to convict a defendant alone without an averment in the indictment regarding the existence of other constituent offenders (para. 95, Judgment).

Nonetheless, in light of the evidence against Lo, the CFA took the view that the jury would have reached the same conclusion in any event. The CFA therefore applied  the proviso and dismissed Lo’s appeal (para. 108, Judgment).



Hectar Pun SC, leading Anson Wong Yu Yat (led by Philip Dykes SC and together with Ferrida Chan), acted for the successful Appellant in Secretary for Justice v Tong Wai Hung FACC 7/2021.

Jason Ko (led by Gladys Li SC, with Lawrence Lau and Kin Lau) acted for the Appellant in HKSAR v Lo Kin Man FACC 6/2021.

Hectar Pun SC

Hectar Pun SC was called to the Bar in 1995 and appointed Senior Counsel in 2015. His practice spans many areas including constitutional and administrative law, human rights law, immigration law, criminal law, land law, company law and commercial law. He appears regularly on behalf of applicants in major judicial review proceedings.

In the area of criminal law, he secured the acquittals of the first and second defendants in HKSAR v Tong Wai-hung and Others ([2020] HKDC 588) (leading Anson Wong Yu Yat) and appeared for the 1st Respondent in Secretary for Justice v CMT [2021] 1 HKLRD 1, where the Court of Appeal clarified the principles on care and protection orders in sentencing juvenile offenders for unlawful assembly during the 2019 protests (leading Jason Ko).

Visit Hectar’s profile for more details.

Anson Wong Yu Yat

Anson was called to the Bar in 2015 and serves as a Member of the Committee on Intellectual Property and Committee on Competition Law of the Hong Kong Bar Association. He has developed a broad civil practice with an emphasis on public law, intellectual property litigations and competition law matters.

Anson is also experienced in handling both civil and criminal matters involving complex issues of law. Recently, Anson acted as junior counsel in two appeals before the Court of Final Appeal determining important questions of law concerning insolvency matters as well as land law and equity: Re Hsin Chong Construction Co Ltd (2021) 24 HKCFAR 98; Cheung Lai Mui v Cheung Wai Shing (2021) 24 HKCFAR 116.

For more details, please see Anson’s profile.

Jason Ko

Jason joined Chambers in 2019 and maintains a broad civil and criminal practice.

In the area of criminal law, Jason (led by Mr. Paul Harris SC in the Magistrates’ Courts; led by Mr. Hectar Pun SC in the Court of Appeal) acted for the 1st Respondent in Secretary for Justice v CMT [2021] 1 HKLRD 1, which concerns a sentence review involving the principles on care and protection orders in sentencing juvenile offenders.  

In Kwok Cheuk Kin v Secretary for Security [2020] 5 HKLRD 653, Jason (together with Mr. Ernest CY Ng) represented the Applicant in judicial review proceedings concerning the Police’s duty to show unique identification at public order events, and the Government’s duty to put in place an effective system of investigation under Article 3 of the Hong Kong Bill of Rights.

Find out more from Jason’s profile.

Disclaimer: This article does not constitute legal advice and seeks to set out the general principles of the law. Detailed advice should therefore be sought from a legal professional relating to the individual merits and facts of a particular case. The photographs which appear in this article are included for decorative purposes only and should not be taken as a depiction of any matter to which the case is related.