John G. Roberts pairs a youthful demeanor with a sharp, seasoned legal mind that has impressed Ivy League professors, government lawyers and U.S. presidents. Befitting his age of 50 and limited time on the appellate court, the book on his judicial decisions remains a work in progress. President Bush on Tuesday tapped Roberts to become the nation's 109th Supreme Court justice, introducing the Harvard honors graduate, former clerk to William Rehnquist and successful Washington attorney to the nation in prime time. "He has argued 39 cases before the Supreme Court and earned a reputation as one of the best legal...