Police have detained activists behind the democracy petition, which has drawn diverse support.
For 12 hours, they questioned him. They brought him water, but no food. And they debated the document that had led him here: Charter 08, a call for sweeping political change in China.
It's gotten to be an old story here: A clutch of activists challenges the government; the government jails one or two to scare others into silence.
But the movement around Charter 08 is different, say human rights groups and Mr. Zhang, who helped draft the document.
A month after its release, Charter 08 is still making waves in China. A wide cross-section of citizens has expressed support online. And the government, nervous about social unrest and the approaching anniversary of Tiananmen Square, has contacted – and in some cases, interrogated and threatened – at least dozens of the manifesto's original signers.
"This text is having a lot of impact – people are debating and signing it online," says Nicholas Bequelin, China researcher for Human Rights Watch. "This is a landmark in terms of its appeal, and [the] attention that it has provoked."
Charter 08 calls for an end to one-party authoritarian rule and lays out a vision for a rights-based society – an electoral democracy, under the rule of law, with equality for peasants and city-dwellers and protected freedoms of speech and expression.
Similar calls have been made before; all have failed to weaken the Chinese Communist Party's grip on power. But activists say this manifesto is significant in several respects.
First, thousands of citizens of all backgrounds – peasants, teenage netizens, prominent lawyers, former party members – have added their names to the petition, not just the usual gadflies. They reflect a minority unwilling to accept the party's vision for China.