A second anti-corruption activist is being tried in China, after the trial of Xu Zhiyong on Wednesday.
Zhao Changqing is charged with disturbing public order and could face up to five years in prison.
Several members of the New Citizens' Movement, a transparency movement led by Mr Xu, are facing trials this week.
Rights groups and Western diplomats have urged the Chinese government - which vowed to fight corruption - to release the activists.
The New Citizens' Movement is a loose network of activists campaigning for officials to declare their assets. It also organises dinner gatherings to discuss social issues.
Members of the movement maintain that they were supporting President Xi Jinping's high-profile campaign against corruption, the BBC's Martin Patience in Beijing reports.
But with the activists now on trial, the ruling Communist Party is clearly showing that it will not tolerate any challenge to its authority, our correspondent adds.
Zhao Changqing's trial started briefly on Thursday, but was paused after he dismissed his lawyer, Zhang Xuezhong.
Mr Zhang told reporters that the move was made in order to delay the trial. Mr Zhao now has 15 days to choose a new lawyer.
Hou Xin, another member, was also scheduled to be tried on Thursday.
Rights groups have described the crackdown on activists as hypocritical.
Brad Adams, Asia director at Human Rights Watch, said on Tuesday: "While Xi Jinping has spoken a lot about tackling corruption and there have been some high-profile arrests, the government has harshly retaliated against those who exposed high-level corruption in the government and party."
Meanwhile, Wang Gongquan, a wealthy businessman considered a key supporter of the movement, was released on bail after confessing to "inciting the criminal activity of assembling a crowd to disrupt public order with Xu Zhiyong", a Beijing court said on its verified microblog.
Xu Zhiyong's lawyer, Zhang Qingfang, described the court's posting as a "complete distortion of facts".
'A better China'
A known legal scholar, Mr Xu also campaigned on behalf of inmates on death row and families affected by tainted baby milk formula in 2009.
At his trial on Wednesday, he initially refused to speak in court because he viewed the proceedings as illegal, his lawyer said.
However, he later spoke for around 10 minutes before he was interrupted by the judge, reports said.
An account of Mr Xu's closing statement was posted online by an activist website and the Chinese language version of Radio France Internationale.
In the account, Mr Xu reportedly said: "By trying to suppress the New Citizens Movement, you are obstructing China on its path to becoming a constitutional democracy through peaceful change."
"Our faith in the idea of building a better China, one of democracy, rule of law, freedom, justice, and love, is unwavering."