The trial for opposition leader Vladimir Kozlov and oil worker Akzhanat Aminov began Thursday in Kazakhstan. The rights organization said both men are on trial for their role in clashes between police forces in oil workers waging a labor strike in Zhanaozen in December.
Late March demonstrations in Kazakhstan came 100 days after clashes between political and protesters in the western Kazakh oil city of Zhanaozen. In June, Kazakh authorities charged some of the demonstrators with plotting a "forcible overthrow of constitutional order" in the country.
Mihra Rittmann, a regional investigator for Human Rights Watch, said strict adherence to international standards is needed during the trials.
"The trial should be open to observers, held in an official language that all the defendants can understand, and the defendants should be allowed to challenge evidence presented against them and cross-examine witnesses," she said in a statement from Moscow.
The men were arrested in January. At least 15 people were killed during last year's oil strikes.