DONGSHIGU, China  Chen Guangcheng is officially a free man, but it is hard to imagine a life more constrained. One of the country’s most prominent rights defenders, Mr. Chen is confined to his home 24 hours a day by security agents and hired peasant men armed with sticks, bricks and walkie-talkies. Visitors who try to see him are physically repulsed and sometimes beaten. Blinding floodlights illuminate his stone farmhouse at night.

With Internet and phone service blocked, he has no contact with the outside world. And the punishment is not his alone: Mr. Chen’s wife and young daughter have been subjected to the same restrictions since he emerged from a 51-month prison sentence last September, widely viewed as retribution for his advocacy efforts against a local family planning campaign of forced abortions and sterilizations.

“I have come out of a small jail and walked into a bigger jail,” Mr. Chen, 39, a blind, self-educated lawyer, said in a homemade video that was smuggled out of his village last week. “What they are doing is thuggery.”

Euphemistically known as “ruanjin,” or soft detention, Mr. Chen’s house arrest is an increasingly common tactic employed by the Chinese authorities as they seek to extend their control over lawyers, democracy activists and underground church leaders who refuse to bend to their will, human rights advocates say.