Despite the gains made by African Americans after the Civil War, Native Americans, Asians, and others not considered "free white persons" were still denied the ability to become citizens. The 1882 Chinese Exclusion Act explicitly denied naturalization rights to all people of Chinese origin, while subsequent acts passed by the US Congress, such as laws in 1906, 1917, and 1924, would include clauses that denied immigration and naturalization rights to people based on broadly defined racial categories. Supreme Court cases such as "Ozawa v. United States" (1922) and "U.S. v. Bhagat Singh Thind" (1923), would later clarify the meaning of the phrase "free white persons," ruling that ethnically Japanese, Indian, and other non-European people were not "white persons", and were therefore ineligible for naturalization under U.S. law.