1. The Respondent was charged with the offence of unlawful assembly upon trailing closely behind a plainclothes police officer (“PW1”) with three other persons and using a video camera continuously to make a recording. 2. After trial, Principal Magistrate Don So (“the magistrate”) found the Respondent guilty and imposed a sentence of 3 months’ imprisonment. The magistrate found, amongst other things, that (1) the Respondent consciously assembled with the other three defendants; (2) their acts insulted and provoked PW1, in particular, the Respondent’s conduct of filming PW1 was provocative; (3) such acts were likely to cause other persons reasonably to fear that those assembled would commit a breach of the peace or provoke other persons to commit a breach of the peace; (4) these acts cumulatively had a greater intimidating effect; and (5) the Respondent was aware of the harassment, threat and provocation directed towards PW1 at the scene and he deliberately participated in the assembly. 3. On appeal to the Court of First Instance, A Wong J (“the Judge”) allowed the Respondent’s appeal against conviction because he could not draw the irresistible inference that the Respondent had the participatory intent. 4. The Court reiterated the law on unlawful assembly previously discussed in HKSAR v Lo Kin Man. With respect to the participatory intent for the offence, it was held that two ingredients are needed to satisfy the requirement: (a) the defendant intended to become part of the assembly; and (b) while he or she assembled together with these other participants and was aware of the related conduct of other participants, he or she intended to engage in or act in furtherance of the prohibited conduct under Section 18(1) of the Public Order Ordinance (Cap 245). 5. This Court held that in the present case the unlawful assembly came into being as the Respondent joined the other defendants in the group trailing closely behind PW1. He had committed a prohibited act under Section 18(1) by the way and the circumstances in which he filmed PW1 in the unlawful assembly. 6. According to the findings of the courts below, the Respondent had the intent to become part of the group of people who pestered PW1 at close distance. This finding was supported by the video recordings which showed that the Respondent rushed towards PW1 together with others in the group. Further, as found by the magistrate and affirmed by the Judge, the Respondent was able to film without objection or fear of reprisal by the others in the group. Thus, ingredient (a) was established. 7. As the Respondent was aware of the related conduct of the other participants and intended to engage in his own prohibited act of filming PW1 while assembled with the other defendants. Thus, ingredient (b) was also established. 8. This is clearly not a case of mere presence or spontaneous filming by an innocent bystander. Had the Judge properly directed himself on requirement of participatory intent, there is nothing to preclude him from drawing the irresistible inference that the Respondent had the requisite intent. 9. Accordingly, this Court unanimously allowed the appeal and restored the conviction and sentence against the Respondent.