In its decision in the case of U.S. v. Bhagat Singh Thind (1923), the Supreme Court deemed Asian Indians ineligible for citizenship because U.S. law allowed only free whites to become naturalized citizens.

What we now hold is that the words “free white persons” are words of common speech, to be interpreted in accordance with the understanding of the common man, synonymous with the word “Caucasian” only as that word is popularly understood. As so understood and used, whatever may be the speculations of the ethnologist, it does not include the body of people to whom the appellee belongs. It is a matter of familiar observation and knowledge that the physical group characteristics of the Hindus render them readily distinguishable from the various groups of persons in this country commonly recognized as white. The children of English, French, German, Italian, Scandinavian, and other European parentage, quickly merge into the mass of our population and lose the distinctive hallmarks of their European origin.

The succeeding years brought immigrants from Eastern, Southern and Middle Europe, among them the Slavs and the dark-eyed, swarthy people of Alpine and Mediterranean stock, and these were received as unquestionably akin to those already here and readily amalgamated with them. It was the descendants of these, and [261 U.S. 204, 214] other immigrants of like origin, who constituted the white population of the country when section 2169, re-enacting the naturalization test of 1790, was adopted, and, there is no reason to doubt, with like intent and meaning.