A Chinese lawyer has been sentenced to seven years in prison in the third of a series of subversion trials demonstrating the ruling Communist party’s determination to shut down independent human rights activists and government critics.

Zhou Shifeng was director of Beijing’s Fengrui law firm that took on sensitive cases and represented people who dared challenge the party.

Zhou accepted the ruling and would not appeal, the official Xinhua news agency reported.

His half-day trial in the northern city of Tianjin followed those of two related legal activists earlier this week, one of whom was sentenced to 7 ½ years and the other given a suspended sentence, both for subversion.

As with the others, Zhou was detained in July of last year amid a sweeping roundup of activists and lawyers. About 300 lawyers and activists were initially seized and questioned before most were released.

Zhou established Fengrui in 2007 and the next year took on one of the country’s biggest dairies in a scandal over tainted baby formula that the government had tried to squelch. The firm has also represented clients targeted by the government, including members of the banned Falun Gong meditation sect and activist artist Ai Weiwei.

Zhou’s final case involved Zhang Miao, a news assistant for the German weekly Die Zeit who was detained for nine months after helping with the magazine’s coverage of pro-democracy protests in Hong Kong. Zhou had been meeting Zhang at a hotel in suburban Beijing following her release when he was seized, hooded and driven away by agents.

This week’s trials were part of a pattern established under president Xi Jinping to use more sophisticated legal means to attack perceived opponents as it maintains pressure on activists and non-governmental organisations.

Several of those detained, including Zhou and fellow Fengrui lawyer Wang Yu, have made televised apologies for their alleged crimes, saying their legal activism was directed by unidentified “hostile foreign forces” to smear and attack the Chinese government.

Fengrui often worked with activists to gather evidence of government abuses and lead clients and the disgruntled in street protests while spreading word online. Their actions were harshly denounced by the authorities as thuggery and interference in the legal process.

Many family members of those being held say they and their retained lawyers have been denied access to the detainees for more than a year, receiving only occasional updates by word of mouth. Some have been briefly detained themselves while seeking information. Zhou and others were assigned government-appointed lawyers who work closely with the court.