A disbanded alliance behind Hong Kong’s Tiananmen Square vigil had only intended to promote democracy and greater political freedom when it advocated the abolition of the mainland’s one-party rule, a defence lawyer has said in a high-profile national security trial.

Defence counsel Erik Shum Sze-man on Wednesday said ending the Communist Party of China’s one-party rule would have been a solution to the political crisis after Beijing’s military crackdown on pro-democracy protests on June 4, 1989.

He said the Hong Kong Alliance in Support of Patriotic Democratic Movements of China did not oppose the party or intend to topple its leadership, as its ultimate aim was to develop a democratic system across the border.

“Concerning the abolition of one-party dictatorship and whether it is equivalent to ending the Communist Party’s leadership, there are lawful means to achieve that,” Shum said, adding that all of the alliance’s objectives were a legitimate exercise of fundamental human rights.

Shum, who spoke on behalf of former alliance chairman Lee Cheuk-yan, outlined the defence’s arguments at West Kowloon Court while cross-examining a police superintendent’s understanding of the principles underlying the organiser’s annual candlelight vigil to mark the 1989 crackdown.

Lee, 68, and former vice-chairwoman Chow Hang-tung, 41, are contesting a count of inciting subversion for promoting an end to “one-party dictatorship”, one of the alliance’s five operational aims. The offence carries a maximum jail sentence of 10 years under the Beijing-decreed national security law.

Ex-alliance vice-chairman Albert Ho Chun-yan, 74, was excused from attending the remainder of the trial after pleading guilty to the charge.