Open this photo in gallery Sun Qian is a Chinese-born Canadian citizen who has been detained for more than a year in China.

Sun Zan struggles to count how many lawyers she has hired − and then lost − as she tries to mount a legal defence of her sister, a wealthy Chinese-born Canadian citizen who has been detained for more than a year in China.

Sun Qian is a Falun Gong practitioner. She was arrested in February, 2017, and charged with violating a Chinese law against superstitious sects, a common legal tool used in China’s long campaign against Falun Gong. Her family expects her trial date will occur before the end of June.

But they have struggled to mount a legal defence for Sun Qian, whose case The Globe and Mail reported last year. The lawyers they hire keep backing out. Some “faced harsh suppression and are not able to take any cases now,” Sun Zan said in a recent interview.

Story continues below advertisement

In total, she believes, she has now hired 11 lawyers. Almost all of them have stopped representing her sister.

Some have been told to drop the case, either directly by authorities or by their own law firms. They have been visited at their homes by police and ordered not to accept media interviews or write about Sun Qian online. One lawyer’s legal licence was cancelled. Another believes he has been placed on a travel security blacklist, since his national identity card often sets off alarms when he passes through security at airports and train stations.

Lawyers willing to represent sensitive cases in China have come under harsh pressure from authorities in recent years. Some have been jailed, others have accused police of torturing them and extracting false confessions.

Even in that context, the harassment of Sun Qian’s legal representation amounts to a remarkable attempt to interfere in the judicial process against a woman jailed for her beliefs, legal experts say. The pressure is notable, too, because Sun Qian is a foreign citizen, and her alleged crime stems from her personal faith. Her case has been raised before the United Nations Human Rights Council and drawn the attention of Canadian parliamentarians. Canadian consular officials regularly visit her and her family has pleaded with the Prime Minister’s Office for help.

In China, meanwhile, her arrest has drawn the attention of the small community of human-rights lawyers.

“Sun Qian’s case is one of the most important cases for China,” said Xie Yanyi, a lawyer who was himself detained for 553 days, but began to represent Sun Qian after his release. “It will influence the fate of tens of thousands of people, and carries great meaning with regard to the administration of the rule of law in China.”

From the day of her arrest, to the mistreatment she alleges at the hands of authorities, “to the day her property was seized, every single procedure was illegal,” Mr. Xie said. “There is nothing lawful in this case.”

Story continues below advertisement

She began practising Falun Gong in 2014, crediting it with curing her of health problems, and became a passionate evangelist.

If her case cannot be “resolved, the Chinese legal system will continue to deteriorate, and no possibility will remain for so-called reform to take place,” Mr. Xie said.

But he can no longer represent Sun Qian. In late April, his licence to practise law was suddenly cancelled. An unusual number of surveillance cameras have been installed near his home. Plainclothes police and domestic security officers regularly follow him.

Another lawyer, Huang Hanzong, was asked to write a statement for the Beijing Lawyers Association, in which he said that he had, in accordance with the orders of justice and security officials, “successfully convinced the family members of both suspects to terminate their commission with me.” (Mr. Huang had also represented Yu Wensheng, a human-rights defender now charged with “incitement to subvert state power.”)

“You may find it unbelievable that a lawyer in Mainland China would be required to write down something like this,” Mr. Huang said in an interview.

He believes the pressure exerted against him is a result of both the Chinese government’s long-standing campaign against Falun Gong and Sun Qian’s Canadian citizenship, which has added to its sensitivity.

Story continues below advertisement

Chinese authorities have allowed lawyers to visit Sun Qian in detention. She appears to be in good health, her sister said.

However, Sun Qian has told her lawyers she has been mistreated and subjected to an intensive re-education effort. In early March, a trio of therapists came three times a week for two weeks in an attempt to persuade her to give up Falun Gong, Sun Zan said. “My sister said they never stopped talking and that made her quite dizzy, so finally she decided she would not answer any of their questions,” Sun Zan said.

At that point, they began playing videos “about the lethal effects of Falun Gong on people. They repeated this sort of thing again and again,” Sun Zan said. It was “a kind of brainwashing,” she said.

Sun Qian has earlier said she was physically mistreated, including being chained for a lengthy period of time and being pepper sprayed. Her family calls it “torture.” Authorities have refused to release video of her interrogation.

Sun Qian was once, together with her husband, a billionaire owner of a biochemistry company. However, her shares in the company have since been transferred to her husband, according to her family, which says the transfer was made fraudulently. Her husband has refused to answer questions about it.

“Why has this case gotten so much attention [from authorities]? I think it’s mainly because the scale of this financial misappropriation is quite huge,” said Liu Hao, her current lawyer, referring to the dispute over share ownership. Mr. Liu began representing Sun Qian in mid-April and has been “continuously told not to write on internet platforms, not to take interview or post articles on WeChat,” he said. WeChat is a Chinese social-media platform a bit like Facebook.

Story continues below advertisement

Other lawyers say the consequences for getting involved in the case of the Canadian woman have been more serious.

“As a result of representing Sun Qian, I have now been deprived of my right to accept commissions on any belief-related cases,” lawyer Gao Chengcai said.

He was ordered to halt his work with Sun Qian by public-security officials, who visited his home on multiple occasions and called him in for talks, at one point telling him, “when we say no, it’s a no. It means you had better stop.”

“It seemed like they thought it would cause harm for our country,” he said.

He believes his national identification card has now been flagged, marking him as a threat to Chinese stability − a serious designation. During major national political meetings, a scan of his card sets off an alarm and he has been surrounded by police and questioned. He was barred from going to Beijing four times last year.

At the same time, authorities pressured his law office, leaving him “in the condition where I must either quit Sun’s case or give up my job. Unwilling to risk my firm’s business, I finally decided to step away and obey their order,” Mr. Gao said.

Story continues below advertisement

He continues to believe in his former client’s innocence.

“You cannot say a person is guilty because his or her beliefs are not popular among the people in power.”