Six people who fled Polytechnic University during unrest in 2019 were found guilty of rioting on Saturday, in the first case involving protesters on the campus.
Deputy Judge Colin Wong said the defendants had been there to advocate unlawful acts of violence.
The District Court heard that a confrontation between protesters and the police occurred in the area on the night of November 17, 2019, with petrol bombs, tear gas and water cannon trucks being deployed at the scene. It also heard that some protesters set fire to the entrance of PolyU the following morning then fled the campus under the cover of thick smoke.
The defendants, who were arrested at the nearby Science Museum on November 18, 2019, claimed either that the prosecution could not prove that they had left PolyU in this way, or that they only been on the campus for innocent and lawful reasons.
The judge said that the six, all aged between 18 and 23, must have left PolyU before arriving at the museum that morning, as the area had been sealed off by officers and no-one could have entered it from elsewhere.
He said that the defendants must have known a riot was taking place at the university and lingered there to boost the momentum of the crowd.
"By doing so, they advocated others to continue the unlawful acts of violence, or to commit unlawful acts of violence," he said in his judgement. "Each of the defendants had the intention to take part in the riot."
Sentencing has been adjourned to December 10.