Race Classification

United States v. Bhagat Singh Thind, 261 U.S. 204 (1923), was a case in which the United States Supreme Court decided that Bhagat Singh Thind, who was an Indian Sikh, settled in Oregon, could not be a naturalized citizen of the United States, because he was not a "white person" in the sense intended in the relevant 1790 statute governing naturalization. Although Thind argued that as an Indian he belonged to the Aryan and therefore the Caucasian race, the Court found that "the Aryan theory, as a racial basis, seems to be discredited by most, if not all, modern writers on the subject of ethnology," and noted that "the Caucasic division of the human family is 'in point of fact the most debatable field in the whole range of anthropological studies.'"

Associate Justice George Sutherland found that, while Thind, an Asian Indian, may claim to have "purity of Aryan blood" due to being "born in Village Taragarh Talawa,near Jandiala Guru, Amritsar, Punjab" and having "high caste" status; he was not Caucasian in the "common understanding", so he could not be included in the "statutory category as white persons".^[1] 

The Court concluded that "The term 'Aryan' has to do with linguistic, and not necessarily with physical characteristics, and it would seem quite reasonable that mere resemblance in language, indicating a common linguistic root buried in remotely ancient soil, is altogether inadequate to prove common racial origin." 

http://en.wikipedia.org/wiki/United_States_v._Bhagat_Singh_Thind