After his second book came out in Hong Kong two years later, he was banned from traveling outside China.
He has yet to see his latest work — about his attempts to run for office — after a friend had a copy confiscated while bringing it into the mainland from Hong Kong.
In 2007 and 2011 Sun tried to win a seat on the local legislature, fully aware that the rubberstamp body was not holding genuine elections.
Police tore down his posters and, the second time, banned him from campaigning at his former campus.
Instead he crept in at odd hours to make speeches to whatever students he could find.
Sun belongs to the older school of Chinese activists who directly provoke the authorities with calls for democracy, whereas the less-confrontational newer generation tries to uphold existing laws, Human Rights Watch Asia researcher Maya Wang said.
“He is respected for his long years of activism and the fact that he has persisted in the face of both harassment and physical threats as well as house arrest,” she said. “From his generation it’s very rare to have somebody who continues to do this.”
Sun believes that if more Chinese also press for change, the party will eventually have to bow to democracy — treacherous words in the tightly controlled state.
“Political reform is necessary for the [CCP]... If they don’t do it right then they may not survive,” he said. “The way forward will ultimately be decided not by the party, but by the people.”