A Chinese artist known for his provocative and irreverent sculptures of Mao Zedong is facing trial on suspicion of slandering the country’s heroes in a case underlining how little criticism is allowed under China’s leader, Xi Jinping.

The trial of Gao Zhen, 69, was set to begin Monday at the Sanhe City People’s Court in Hebei province, according to his wife. Gao, who has been in detention for more than a year and a half, faces up to three years in prison if convicted. The trial will not be open to the public, a measure that under Chinese law is largely reserved for cases that touch on national security.

“Secret trials are usually a bad sign,” his brother, Gao Qiang, said. “The authorities may have already decided for the court what the outcome should be, and the trial is simply a politicized legal process, devoid of any fairness.”