The Jayapura District Court has opened proceedings against 16 Papuans allegedly involved in a protest against US mining giant Freeport-McMoRan that left five security officers dead.
The Jakarta Post reports that the defendants face charges of destruction of public property and participating in riots that led to the deaths.
They could face prison terms of up to 15 years.
The defendants are being tried in eight separate hearings by a three-member panel.
All the trials were adjourned until next week, when the defence case will be heard.
The men were all detained after the March 16 riots, in which three policemen and an air force officer were bludgeoned to death as hundreds of gun-toting security forces tried to break them up.
Another policeman later died in a hospital.
The Freeport mine is frequently accused by environmental groups of pollution and earning billions of dollars from gold and copper mining at the expense of the local population.
This month, Indonesia's House of Representatives confirmed that the tailing system used by Freeport in its operations at Timika, has caused severe damage to the environment.