BEIJING, July 2 -- For a child entering kindergarten in Tibet this autumn, the question of which language fills the classroom will no longer rest with the school, the teacher, or the family. As of Wednesday, it is settled by statute.

China's ethnic unity law came into force July 2, the most sweeping legislative attempt to standardize national identity across the country's 56 recognized ethnic groups since the founding of the People's Republic. Passed by the National People's Congress on March 12, the law mandates what Beijing describes as a "shared" national consciousness, one that human rights organizations argue amounts to the state-directed absorption of distinct languages, cultures, and traditions into a Han Chinese frame.

The law d...