White by Law is the first systematic study of how law creates and maintains race. Focusing on racial prerequisite cases, Haney López sheds light on key issues related to the legal construction of race, notably, the mechanisms by which courts and legislatures created race, and the conscious and unconscious role of legal actors, such as judges and justices, in these processes.

Following other critical race theorists, Haney López asserts that “race is nothing more than what society and law say it is” (73). The inability of courts to arrive at fixed definitions of whiteness underscores the social nature of race. Courts took a wide range of factors into account when determining white racial identity, including skin color, facial features, country of origin, ancestry, and culture. Unable to establish clear parameters for “white persons,” courts instead determined, on a case-by-case basis, who was not white. Race is a social construct, and therefore notions of whiteness and non-whiteness shifted over time, resulting in inconsistent and at times contradictory court rulings. In Ozawa, for instance, the Supreme Court followed scientific definitions of race, arguing that skin color did not correlate well with racial identity. A few months later, in Thind, the same justices rejected science and their own ruling in Ozawa, instead citing commonly held beliefs in their definition of whiteness and non-whiteness: “The average man knows perfectly well that there are unmistakable and profound differences between [Scandinavians and Indians] today’” (63).