Despite his background in journalism, Cui Yongyuan is on any measure the most unlikely celebrated whistle-blower to take on the rich and famous and powerful in China.

After all, he used to be one of them. He was one of China’s most renowned television chat show hosts back in the late 1990s and early 2000s, during which time he interviewed senior Chinese officials, once hosted and twice appeared in comedy skits in the annual Lunar New Year galas broadcast on national television and watched by hundreds of millions of people.

But in recent years, he has become better known for transforming himself into a unique kind of whistle-blower by using his influence and his wildly popular social media platforms.

Early last year, his public allegations about tax evasion by Fan Bingbing, one of China’s highest-paid actresses, triggered a nationwide tax audit of all of the country’s leading entertainment personalities, who were later forced to cough up tens of billions of yuan in overdue taxes and fines.

Towards the end of last year, Cui started to take on the Supreme People’s Court and its president Zhou Qiang by championing the cause of an ordinary businessman who was embroiled in a 12-year legal case against powerful local officials over a coal mine with a potential value of over 100 billion yuan (US$14.7 billion).

Cui’s latest crusade has forced China’s leadership to set up a special task force to look into his allegations about the missing case files of the disputed mine and purported collusion between the local officials and the supreme court judges. As the incident is still snowballing, there is speculation about whether his latest whistle-blowing act could trigger a political earthquake at the supreme court or even implicate more powerful officials.

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Cui, who turns 56 next month, was a journalism major, and became a radio and TV journalist after university. In 1996, he hosted a talk show called Tell It Like It Is, which he helped launch, on China Central Television and this propelled him to national fame. His self-deprecating, caustic humour and folksy presentation style proved widely popular with the Chinese audience. After a six-year runaway success with the show, Cui disappeared suddenly from public view in 2002. It later transpired that he was experiencing depression and was suicidal for some time, partly because of the high-intensity work life. He returned to work a year later and continued to host new shows and dabble in documentary-making.

Described as a man honest about his own feelings, he is prone to court controversies. Cui has often used his fame and social media influence (he has 20 million followers on Sina Weibo, the Chinese equivalent of Twitter) to weigh in on pressing social issues and blast his critics, with his signature caustic tone and frequent liberal use of expletives.

Around the time he left China Central Television in 2013, he stirred up a national debate over safety of genetically modified food by voicing vehement opposition to such products and exchanged heated and often personal attacks with supporters of genetically-modified food over the internet and social media. His strong opposition against GM food has greatly impacted how it is viewed in China.

The fact Cui’s whistle-blowing could lead tax authorities to take the decisive action against a long-standing issue has raised speculation he must have powerful political supporters

Last May, Cui triggered an even bigger national scandal by accusing Fan of greatly under-reporting her earnings to tax authorities, a practice known as “yin and yang” dual contracts. His allegations were prompted by a personal grudge against Fan and a film director for shooting a sequel to the film Cell Phone (2002), which satirises the life of a famous talk show host – a story which he said had similarities between the lead character and his own experiences.

Until Cui’s allegations, the tax authorities had largely turned a blind eye to the widespread practice of dual contracts in China’s entertainment industry with the sole purpose of tax evasion, not least because many leading entertainers have strong political patrons. But his assertions have brought an abrupt change in the attitude of the tax authorities, which ordered an immediate investigation into Fan’s tax situation and that of her companies despite her initial denial of wrongdoing.

Fan was ordered to pay 884 million yuan in overdue taxes and fines following the probe. The tax authorities also launched a comprehensive audit of leading entertainers, starting from October. On Wednesday, Xinhua reported that China’s celebrities and their companies “voluntarily” paid a total of 11.7 billion yuan in overdue taxes.

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That Cui’s whistle-blowing could single-handedly and promptly lead the tax authorities to take action against the long-standing issue has raised speculation that he must have powerful political supporters himself – something he does not explicitly deny.

Just as the tax scandal died down, Cui triggered another major political firestorm by throwing himself into a growing political scandal over the coal mine case involving the former party chief of Shaanxi and senior judges at the supreme court.

The scandal has arisen from a legal dispute over a deal between a private businessman and a Shaanxi provincial government-owned geology entity to jointly explore a large coal mine. The government entity later broke the agreement and transferred the mining rights to a company owned by a Hong Kong-based woman, who was reportedly close to Zhao Zhengyong, the former party chief of Shaanxi. Since 2006, the two parties have disputed the ownership of mine rights through lawsuits at the provincial supreme court and the national supreme court.

Since 2010, several major influential publications, including China Youth Daily and Caixin, have carried detailed investigative reports about the irregularities of the long-running disputes, including the allegation that the Shaanxi provincial government issued an internal request to the national supreme court to plead for a favourable ruling for its provincial entity. Such an act is an illicit interference in legal affairs.

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But those reports failed to capture the imagination of the nation until Cui fired an expletive-laden Sina Weibo post focusing on why case files on the disputed mine were missing from the supreme court and calling out the supreme court president. The next day, the court denied Cui’s allegations but two days later admitted Cui’s allegations were valid and promised to launch an investigation. Then a videotape of a national supreme court judge presiding over the case was leaked to the press, showing him strongly hinting that the case files were stolen from his office and that CCTV cameras installed outside his office were sabotaged when the documents disappeared. The case files were supposedly missing in late 2006 but this was not known until Cui’s allegations surfaced two years later.

Also leaked online was the first page of a classified supreme court document on the mine case, showing the directives of Zhou and other senior judges on how to keep the case secret.

On January 8, the Chinese leadership announced that a joint task force, comprising of anti-graft investigators, prosecutors, and police, had been formed to look into the case of the missing files from the supreme court.

Cui immediately reposted the official announcement on his Sina Weibo and later told media that he took on the national supreme court to uphold justice and educate the supreme court about law.

Wang Xiangwei is the former editor-in-chief of the South China Morning Post. He is now based in Beijing as editorial adviser to the paper