The trial of a Chinese activist, who is at the center of a year-long government crackdown on legal activism, is set to begin in Tianjin.
Zhai Yanmin is one of a group of four activists and lawyers accused of “subversion of state power”.
A prominent lawyer from the same firm, Wang Yu, was reportedly released on bail on Monday after a video appeared in which she renounced her legal work.
About 300 lawyers and activists have been detained in recent months.
Observers have said the cases are politically motivated and human rights groups have called on China to release them.
The charge of subverting state power carries a maximum penalty of life imprisonment.
‘Ridiculous and evil’
The group is widely known as “709” – a reference to the date the crackdown was launched on 9 July 2015.
The families of some of those arrested said in a statement on Monday that the trial was “ridiculous and evil”.
“As 709 family members, we solemnly make this appeal to Chinese citizens and international friends, please pay attention to and condemn the trial.”
The statement also alleged that the wife of Mr Zhai was missing, with others facing at risk of being “taken away”.
The family members said they were not being allowed to attend Tuesday’s trial.
But on Tuesday, some relatives and supporters gathered outside the Tianjin No 2 Intermediate People’s Court, along with journalists and police.
Xinhua, the state media agency, said the trial would be open to observers and that 28 people were expected to attend, including “12 representatives from domestic media and five others from international media”.
Human rights lawyer Zhou Shifeng and the two other activists, Hu Shigen and Gou Hongguo are also expected to go on trial over the next four days.
In a video released on Monday, Ms Wang denounced Mr Zhou, the law firm’s head, as an unqualified lawyer.
She added that “foreign forces” were using her law firm to undermine and discredit the Chinese government.
Observers said there were indications the “confession” was coerced. In recent months forced public confessions have been used in several cases in China.