The Supreme People's Court opened an appeals trial for Cu Huy Ha Vu, who was sentenced last April to seven years in jail for anti-state propaganda.
Reporters from 14 local press agencies and eight foreign agencies were allowed into the courtroom Tuesday. Vu's first trial was closed to the press.
Four lawyers defended Vu at the trial.
The Hanoi People's Court on April 4 sentenced Vu, 54, to seven years of imprisonment for distributing propaganda against the State.
Vu was charged under Article 88 of the Criminal Code, which carried a jail term of three to 20 years. He will also be put under house arrest for three years after serving the seven-year sentence.
According to the indictment, Vu posted articles and interviews with foreign media criticizing the state between 2009 and 2010.
The articles and interviews allegedly maligned Party and State guidelines and policies, defamed the administration and State institutions, and blackened the legacy of Vietnam's resistance wars.
The judges said Vu's acts "put the society in danger and violate the interests of the State and the people."
Last November, Ho Chi Minh City police arrested Vu at a hotel in District 6. The Ministry of Public Security's police later searched his house and seized his documents.
After the first trial, Vu appealed to the Supreme People's Court.
Vu is the son of Cu Huy Can, who was a member of revered founding president Ho Chi Minh's provisional cabinet and a celebrated poet, and a nephew of Xuan Dieu, also one of the country's famed poets.
Vu obtained a doctorate in law in France and ran a law firm with his wife in Hanoi before being detained.