Pu Zhiqiang, the noted lawyer who spoke against China's one party system and accused the government of using excessive force against Uyghur Muslims in Xinjiang, is accused of "inciting ethnic hatred" and "picking quarrels and provoking trouble".
A large group of aggressive policemen in plainclothes many of them wearing yellow smiley-face badges - pushed, punched and harassed reporters, camera-crews and diplomats away from the front of the court.
The trial ended with no verdict announced but China's ruthless suppression of dissent was caught on video cameras as police pushed and shoved foreign journalists and diplomats away from the court and made attempts to seize the cameras.
Pu, who is in court over comments made on social media, is the latest to be tried in a crackdown on lawyers, dissidents and those accused of corruption.
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The lawyer faces up to eight years in prison if convicted, the BBC reported.
The court has not said when it will announce the verdict.
Given the government's tight control of the courts, there is almost no chance of an acquittal and Pu probably faces a lengthy spell in prison, the report said.
Pu had posted several messages on microblogging platform Weibo questioning the authorities' "excessively violent" crackdown on Uyghurs in the restive Xinjiang region, where Chinese forces are cracking on East Turkistan Islamic Movement (ETIM) blamed for a number of violent incidents.
He also alleged the Chinese Communist Party was an untruthful party and mocked government rhetoric over the disputed islands with Japan.
In his final remarks in court,Pu thanked his friends as well as the detention centre which "treated me well", and added that he was willing to apologise if his posts had ever harmed anyone, said his lawyer Shang Baojun.
Outside the court, a small group of Pu's friends and supporters held a protest.
The Foreign Correspondents Club of China condemned the manhandling of journalists, saying that at least one journalist was "slammed to the ground" by a security officer while others were pushed, shoved and punched in the back.
Amnesty International says there have been "repeated procedural irregularities" in his prosecution.