Ozawa v. United States,
260 U.S. 178 (1922)

¢Manifestly the test afforded by the mere color of the skin of each individual is impracticable, as that differs greatly among persons of the same race, even among Anglo-Saxons, ranging by imperceptible gradations from the fair blond to the swarthy brunette, the latter being darker than many of the lighter hued persons of the brown or yellow races. Hence to adopt the color test alone would result in a confused overlapping of races and a gradual merging of one into the other, without any practical line of separation.