He has been briefly jailed several times for offences such as shouting from Legislative Council of Hong Kong (LegCo) public viewing gallery, burning the national flag of the People's Republic of China and forcibly breaking into an opposition political event. In 2000, he and Koo Sze-yiu were prosecuted for disrupting a LegCo meeting and were later jailed for 14 days, becoming the first dissents to be jailed after the handover of Hong Kong in 1997. Before that he had been charged for 14 times, 11 of which were convicted.