At about 7:30 am, Sokha and his team of lawyers arrived at the court where dozens of police and military officers were deployed to ensure security and public order.
Kem Sokha, 64, was detained in 2017 for for the charge of “colluding with foreigners” under Article 443 of Cambodia's Criminal Code.
More than two months after his arrest, the CNRP was dissolved by the Supreme Court and 118 senior party members banned from joining politics for five years.
On September 10 last year, he was released from Trapeng Phlong Prison in Tbong Khmum province and but immediately put under house arrest to serve investigation of his alleged crimes.
According to the court, Kem Sokha was granted bail due to health reasons, with legal assurances he could not flee the court proceedings.
Two months later, he was freed from house arrest.
Sokha could face up to 30 years in prison if found guilty.