The top court has unanimously overturned the public order convictions of two social activists for disrupting a government minister's speech to protest against higher train fares.
However, a legal academic does not believe the judgment will open the floodgates to more radical demonstrations. He felt it affirmed the authority of the police to recommend that magistrates impose a good behaviour bond on protesters whose breach of the peace is not a criminal offence.
Such people will not be charged with an offence if the police deal with them using a binding-over order.
In the Court of Final Appeal yesterday, Mr Justice Patrick Chan Siu-oi noted that Hongkongers had a fundamental right to air grievances and to express views on matters of public interest in a free and democratic society.
But Chan added: "Violent or unlawful means cannot justify an end, however noble."
In April 2011, Chow Nok-hang and Wong Hin-wai rushed onto the stage as Eva Cheng, then secretary for housing and transport, was speaking at a prize-giving ceremony for an MTR Corporation charity race-walking event.
Chow scattered "hell money" - traditional paper offerings for the dead - while Wong, of the League of Social Democrats, snatched Cheng's microphone. They were charged under the Public Order Ordinance with behaving in a disorderly manner in a public place.
A magistrate imposed a sentence of 14 days' jail, which was replaced upon the pair's appeal to the Court of First Instance by fines totalling HK$5,000.
Yesterday, the five Court of Final Appeal judges - Chan, Mr Justice Roberto Ribeiro, Mr Justice Robert Tang Ching, Mr Justice Henry Litton and Lord Millett - rejected a prosecution request to reinstate their jail terms.
They said the pair could have been charged with common assault and put on a good behaviour bond to keep the peace.
"If [Wong] had been charged with common assault, he may very well have been convicted," Ribeiro said. A binding-over order might have been justified in Chow's case, he said.
The judges also noted the ceremony was interrupted for about a minute, and the evidence did not show an intention to "prevent" it from taking place.
Eric Cheung Tat-ming, principal law lecturer at the University of Hong Kong, said protesters who resorted to unlawful means could still be punished, despite the ruling.
The Department of Justice said it was studying the judgment to ascertain its impact.
Outside court, Chow said: "Our decision to protest … depends on whether there is injustice in our society."