The police held Mr. Chui for a few hours before releasing him to seek treatment at a hospital. He told RTHK that he had been asked to sign a “note of remorse” before being freed; he said he did so because he was uneasy about his confiscated ID and the officers’ aggressive behavior.

“We are extremely angry about the unjustified and brutal obstruction that resulted from a legal interview,” Now TV said in an article about the episode.

Ms. Yuan, the rights lawyer’s wife, said he had also been roughly handled by the police and forced into a police car after asking officers to return Mr. Chui’s ID. She said marks were left on his neck. After Mr. Xie’s hearing, the couple were not allowed to photocopy documents from it.

“They want this hearing to occur in secret,” she told RTHK.

Patrick Poon, a Hong Kong-based researcher for Amnesty International, said that the officers’ behavior was likely a response to unwanted media attention at the hearing. “It shows that the authorities are very much aware that the hearing itself isn’t a fair one,” he said.

The incident came just days after another journalist for a Hong Kong television station, Chen Ho-fai, was assaulted in mainland China while covering a politically sensitive event. Mr. Chen of i-Cable was kicked and beaten by two men while reporting on the 10th anniversary of the earthquake in Sichuan Province that killed tens of thousands of people. Shoddy building standards may have contributed to the toll, making it a delicate subject for China.