By 1994, Ruben Castillo had built up a resume that earned him a nomination to the federal trial court in Chicago. Castillo practiced at Jenner & Block LLP and Kirkland & Ellis LLP, handled civil rights work that included helping create the first Latino-majority congressional district in Illinois and tried more than 40 cases as a federal prosecutor. But a colleague in the U.S. Attorney’s Office had a different explanation for Castillo’s selection for a federal judgeship at age 39. “In five seconds, she minimized …