Skip to main content

3. Unlawful assembly (Section 18 Public Order Ordinance)


An unlawful assembly is when 3 or more people assemble together and behave in a disorderly, intimidating, insulting or provocative manner that causes a reasonable fear that a breach of the peace may result of that behaviour. The fear of a breach of the peace may be the intention of the people behaving in that manner, or it may be a likely reaction of other people in the nearby the people behaving in that manner. A person convicted with taking part in an unlawful assembly is liable to imprisonment of 5 years on indictment, or a fine of $5,000 and imprisonment of 3 years on summary conviction.


The Court of Appeal has laid down the sentencing principles of the offence of unlawful assembly: If the case is of a relatively minor nature, such as when the unlawful assembly was unpremeditated, small in scale, involving very little violence, and not causing any bodily harm or damage to property, the court may give proportionally more weight to such factors as the personal circumstances of the offender, his motives or reasons for committing the offence and the sentencing factor of rehabilitation while proportionally less weight to the sentencing factor of deterrence; if the case is a serious one, such as when the unlawful assembly involving violence is large-scale or it involves serious violence, the court would give the two sentencing factors, namely punishment and deterrence, great weight and give very little weight or, in an extreme case, no weight to factors such as the personal circumstances of the offender, his motives or reasons for committing the offence and the sentencing factor of rehabilitation. (Secretary for Justice v Wong Chi Fung [2018] HKCFA 4, [123])


It does not matter whether the assembly started out as a lawful assembly. If 3 or more people in that assembly acted in a disorderly, intimidating, insulting, or provocative manner together and cause a reasonable fear that a breach of the peace may result, it will become an unlawful assembly.


“3 or more persons, assembled together”

This element reflects the ‘corporate nature’ of this offence. The unlawful assembly is made up of those who behave in the prohibited manner. Therefore, if there was only one person out of those who assembled together conducted himself in the prescribed manner, he could not be guilty of this offence.


Where a group of people assembled at a location and only three or more amongst them behave in the prohibited manner, it is they, not other members of their group who do not conduct themselves in such manner, who become an unlawful assembly.


There must be sufficient connection between the conducts of those who behave in the prescribed manner to justify having them considered together. Therefore, if 3 persons in a lawful assembly committed acts of the prescribed nature at different parts of the place of assembly for different purposes, sparking off different incidents, involving and affecting entirely different mix of persons, there would not sufficient nexus to turn these independent acts into an unlawful assembly. But “sufficient nexus” is only an “important factor” in considering whether those persons were acting together, and evidence of a common purpose is only “the best or one of the most important pieces of evidence” to prove that they were so acting together. A common “purpose” does not require a “common motive”, for example the common purpose to attack police officers qualifies as a “common purpose”.


“Disorderly, intimidating, insulting or provocative manner”

What amounts to “disorderly, intimidating, insulting or provocative manner” is a matter of common sense and ordinary meaning of these words. It depends on the time, place and circumstances of the conduct in question.


“Disorderly conduct” has been interpreted as “unruly or offensive behaviour”, “rough or aggressive behaviour”, or “acting in a way which disrupts public order or is against morality”. It does not need to involve any violence or cause serious disruption of public order.



The fear is not about fear as to anyone’s own safety or security. Instead, it is a reasonable fear that a breach of the peace will result. (HKSAR v Leung Kwok Wah [2012] 5 HKLRD 556)


“Taking part”

  1. The offence under section 18 is a participatory offence and requires all involved offenders to be “assembled together” and “conduct themselves” in the prohibited manner. It is not enough for the defendant to have been engaging in the prohibited conduct alone. They must have acted as a part of the assembly with other participants. All participants who “took part” in the assembly will have committed the offence under section 18. (HKSAR v Lo Kin Man (2021) 24 HKCFAR 302, [15]). “Taking part” is the offending act.


  1. Taking part is a broad expression and is not confined to the prohibited acts set out in Public Order Ordinance section 18. Mere presence does not give rise to criminal liability. But a defendant also takes part in an unlawful assembly if they act in furtherance of such prohibited acts by, for instance, facilitating, assisting, or encouraging active participants of the same. A person who provides encouragement, whether by way of words, signs or actions, may face liability as an aider and abettor of active participants or as a principal offender under section 18. (HKSAR v Lo Kin Man (2021) 24 HKCFAR 302, [109(d)])


  1. That a person took part in an unlawful assembly or riot may be proven by way of inference. The following evidence can support an inference of “taking part”:
    1. Time and place of arrest
    2. Items found on the defendant (e.g. helmet, body armour, goggles, a respirator, a radio transceiver, plastic ties, laser pointers, weapons and materials to make weapons such as petrol bombs) (HKSAR v Lo Kin Man (2021) 24 HKCFAR 302, [78]).


“Participatory intent”

  1. It must be proved that the defendant had participatory intent. This means that he intended to take part in the unlawful assembly and engage in or act in furtherance of the prohibited conduct, and was aware of the related conduct of other participants at the time. Proof of such participatory intent may generally be inferred from conduct (HKSAR v Lo Kin Man (2021) 24 HKCFAR 302, [48]).  There is no requirement for the prosecution to prove any extraneous common purpose.
  2. There is no need for the Prosecution to prove that the defendants intended to mutually assist each other.


Joint enterprise

  1. The basic form of joint enterprise doctrine is not applicable because the element of “taking part in” already covers joint liability. A defendant cannot be fixed with liability as a principal offender if that defendant was not present or acted as part of an assembly with the other assembled people. But he can be criminally liable as a counsellor, procurer, conspirator, or inciter.


  1. Extended form of joint enterprise may be applicable to where there was proven foresight of a more serious crime committed in the course of an agreed plan of unlawful assembly or riot.  For example, if a participant of an unlawful assembly or riot is proven to have foreseen that the offence of wounding with intent to cause of inflict grievous bodily harm or murder may be committed, that participant may be found guilty of wounding with intent or murder even when that participant was not the party inflicting the grievous bodily harm or committing the murder (HKSAR v Lo Kin Man (2021) 24 HKCFAR 302


“Mens Rea of the Likely limb”

It must be proved that the defendant and at least 2 other people intended to assemble and conduct themselves in the manner described. However, it is not necessary to prove that the defendant intended for reasonable fear to be a likely consequence of his conduct. Whether said fears were a likely result of the defendant’s conduct is to be determined objectively and independently of what the defendant intended. (HKSAR v. Leung Chung Hang Sixtus (2021) 24 HKCFAR 164)