Clarence Thomas Officially White

"All the judges are white and/or old; most are both."

The above statement is from a Newsweek column by Dahlia Lithwick. Now, I admit that there is nothing about Clarence Thomas's voting record on the U.S. Supreme Court to indicate he is a member of the group descended from Africans who were enslaved, but I hadn't realized that he is considered to be white. Or, is it that Ms Lithwick forgot about him altogether?