As early as 1846, the powers that be in California were setting the stage for legal indenture, or enslavement, of Native Americans.
Captain John B. Montgomery was commander of the U.S.S. Portsmouth stationed at Yerba Buena, later known as San Francisco, when he received orders to claim the town for the United States. Montgomery placed an American flag at the Plaza on July 9, 1846 and worked with Lieutenant Washington Bartlett, a junior officer on the Portsmouth, over the next five months to organize a local government for San Francisco.
In September, 1846, Montgomery issued the following proclamation. On the surface, it appears to guard the Natives against illegal capture and enslavement, and in fact the title of the San Francisco history page where the proclamation is posted is called “End of Indian Slavery in San Francisco”. But if you read closer, the wording simply transferred control of those natives from non-Americans to Americans by requiring those wanting Indian servants to obtain a contract from an American Justice. It also requires that all natives “obtain service”, so they had to work for someone or risk “arrest and punishment by labor on the public works”.