BEIJING  Liu Xiaobo, one of China’s most prominent advocates of democratic change, was tried Wednesday on charges of subversion, a sign that Chinese leaders are reducing their already limited tolerance for peaceful political dissent.

Mr. Liu, an essayist and social critic who has spent more than a year in detention, faces up to 15 years in prison if convicted of charges legally defined as “incitement to subvert state power.” His lawyer said a verdict in the closed trial was likely to be announced on Friday. Charging one of the best-known dissidents with subversion is a disheartening milestone in the eyes of some Chinese legal experts and human rights advocates.

China has rarely brought political charges against people advocating peaceful dissent in recent years, though it often accuses those who offend the authorities of other crimes, like tax evasion, leaking state secrets or violating business regulations.

Now, flush with record foreign exchange reserves and buoyed by the world’s most resilient major economy, Chinese officials seem less hesitant to call a crackdown by its own name: the charge of subversion has now been brought against not only Mr. Liu but also Hu Jia, an AIDS activist and environmentalist, who was convicted of that crime last year and sentenced to three and a half years in prison.