To this day, if you want to bring chills to the spines of conservative Republicans, just mention the name David Souter. Souter was appointed to the Supreme Court in 1990 by President George H.W. Bush because he was mild-mannered and thought to be able to avoid the bruising confirmation fight that snared Robert Bork. “He seemed to have felt a commitment to his conservative philosophy for about six months, and then just fell off a cliff into the dark side of liberalism,” said John Sununu, a fellow New Hampshire native and former governor and senator from the Granite State, who...