Richard and Mildred had married in Washington D.C. But had they actually sought to wed in Virginia, Richard, who had grown up in an area known for its mixed-race families, may not have been able to make such a declaration.

Despite this messy reality, the state’s prosecution of the Lovings was based on the presumption, long disproved by social science, that there was indeed such thing as a “pure” white race to protect. Chief Justice Earl Warren saw through this and clearly recognized the distinction between race as a social category based on a person’s physical features and race as a scientific fact. He declined to embrace the second idea, and referred at one point to “racial categories” and “so-called” races at another.

The lawyers involved in the case, in arguing that the marriage statute should be struck down, ridiculed the idea that “pure races” ever existed and denounced as abhorrent claims that intermarriage with African-Americans produced mentally or emotionally defective children.

One of the lawyers also reminded the court that Virginia’s definition of what it meant to be black had shifted over time in ways that defied rational explanation: In 1705, he said, a Negro “was a person with one-eighth or more Negro blood and then in 1785, it became a person with one-quarter or more, and it went on and on.”

It wasn’t until 1930, he said, that Virginia finally arrived at a definition in which a Negro was someone with any traceable Negro blood.

Chief Justice Warren quizzed Virginia’s lawyer about the falseness of the racial purity claim, yet he veered away from it in his decision for the unanimous court. While the decision acknowledged that the law was written in service of white supremacy, the court found that the statute violated the equal protection and due process clauses of the Constitution by preventing marriage based solely on person’s racial classification.