Xu Zhiyong helped found the New Citizens Movement, which at the time organized monthly dinners to discuss China's constitution and other legal issues.
Zhang Qingfang, Xu's attorney, said he was freed Saturday morning from a prison in Beijing. He says Xu is in good health and that he had no further details to share.
It was not immediately clear if despite his release Xu's movement continued to be restricted. Authorities commonly place activists seen as politically sensitive under some form of house arrest to prevent them from speaking publicly.