Ai told reporters that police the previous night had ordered him to stay home and steer clear of the courts. He said he agreed.
Chinese authorities detained Ai for three months last year and his design company was ordered to pay 15 million yuan ($2.4 million) in back taxes and fines, a penalty interpreted by activists as punishment for his criticism of the authoritarian government.
The company has appealed the fine and separately filed a lawsuit that accuses the tax bureau of violating laws in handling witnesses, evidence and company accounts in the case.
To the surprise of many, the lawsuit was accepted.
Ai's wife Lu Qing, who is the legal representative of his design company, Beijing Fake Cultural Development Ltd., went to the hearing with several lawyers and an accountant.
Plainclothes and uniformed police were stationed outside Ai's home and studio in northeast Beijing on Wednesday, registering journalists who showed up to interview Ai and report on his case. Ai argued briefly with them and demanded to know why they were interrogating his visitors. Reporters were also blocked from filming at the courthouse.
Liu Xiaoyuan, a legal consultant who has been staying at Ai's home, was missing Wednesday after being taken away by police Tuesday night, Ai said.
Since he emerged from detention last year, Ai has been refused permission to travel and is under constant surveillance. He still frequently criticizes the government on Twitter, which is blocked in China but accessible to tech-savvy citizens.
A sculptor, photographer and installation artist, Ai has increasingly used his art and online profile to draw attention to injustices in Chinese society and the need for greater transparency and rule of law.
Before his own detention last April, he was using Twitter to publicize the disappearance of fellow activists in a widespread crackdown by the government.
He has also spoken out about a number of national scandals, including the deaths of students in shoddily built schools that collapsed during the 2008 Sichuan earthquake, children killed or sickened by tainted infant formula and a deadly high-rise fire in Shanghai that killed 58 people and was blamed on negligent workers and corrupt inspectors.
Ai's tax bill prompted tens of thousands of Ai's supporters to send small donations that ended up totaling nearly 8.7 million yuan ($1.4 million), which was used to pay a guarantee to the tax bureau. Some donations were folded into paper airplanes or wrapped around fruit and thrown over his gate.
He was given a symbolic 100 euro ($137) donation from the German government's human rights commissioner.
Ai has said that he will not treat the money from supporters as donations, but as loans that he would repay.
(Copyright 2012 by The Associated Press. All Rights Reserved.)