四五运动
In 1975, he co-founded the Revolutionary Marxist League, a Trotskyist vanguard party, in which he became active in political actions. He was arrested multiple times, including in the protests of supporting the 1976 April Fifth Tiananmen Incident and Chinese democracy movement. His first prosecution was in 1979 when he protested for the Yau Ma Tei boat people. Later in the same year he was charged and jailed for a month for "unlawful assembly" for a protest at the Victoria Park.