Vietnam has charged Le Cong Dinh, an outspoken human rights lawyer, with trying to overthrow the state, a crime that could incur the death penalty.
The charges accuse Mr Dinh with “colluding with Vietnamese reactionary groups and hostile forces in exile” to bring down the Vietnamese state.
Mr Dinh, 41, is secretary of the Democratic Party of Vietnam, a US-based group Hanoi considers to be a reactionary organisation. The party says it is committed to the peaceful pursuit of reform.
Mr Dinh has been a long-standing thorn in the side of the Vietnam Communist Party, using his court appearances on behalf of dissidents and free-speech advocates to agitate for democracy.
Appearing in 2007 for Nguyen Van Dai and Le Chi Cong Nhan, both labour activists, Mr Dinh told the court, “Talking about democracy and human rights cannot be seen as anti-government unless the government itself is against democracy.”
He has also angered the authorities by publicly wading into some of the country’s most sensitive controversies, including a territorial dispute with China over islands in the South China Sea and a deeply divisive plan to mine bauxite in the Central Highlands.
Mr Dinh was originally arrested in June, charged with distributing propaganda against the government. That crime carried a possible 20-year penalty.
Mr Dinh was educated in the US and is a former vice president of the Ho Chi Minh Bar Association. Thanh Nien newspaper said the trial of the four men is expected to start within the next two weeks.