Answer: John Roberts
Explanation: The longest serving Justice was William O. Douglas who served for 36 years, 7 months, and 8 days from 1939 to 1975. A year later, the President nominated her as an Associate Justice of the Supreme Court on May 10, 2010. She took her seat on August 7, 2010. Kavanaugh was officially confirmed by the Senate on Oct. 6 in a 50-48 vote. He was sworn-in by Chief Justice John Roberts hours later in a private ceremony. Kavanaugh was nominated to the U.S. Court of Appeals for the D.C. Circuit by President Bush in 2003. His confirmation hearings were contentious; they stalled for three years over charges of partisanship.