Discriminatory laws were mostly enacted according to national origins, but also involved racial typologies developed by scientific racism theorists. While those who were racially Asian were excluded from obtaining U.S. citizenship, immigration from Asian countries was not entirely barred. A small quota allowed for the emigration of white residents from these countries. These racial naturalization requirements necessitated the more concrete ideation of the category of “Asian” as distinct from white so immigrants could be rejected on the basis of race instead of national origin. This need was quickly supplied by a plethora of judicial rulings and pieces of legislation focused primarily on classifications based contradictorily on phenotypic features, scientific objectivism, and “common knowledge”, depending on the case. The two most important cases are "Ozawa v. United States" (1922) and "United States v. Bhagat Singh Thind" (1923).