What is the middle name of the Associate Justice of the Supreme Court who John F. Duffy served as clerk?
John F. Duffy:  He previously served as law clerk to Antonin Scalia, Associate Justice of the Supreme Court of the United States, and Stephen F. Williams, Judge of the United States Court of Appeals for the District of Columbia Circuit. Antonin Scalia: Antonin Gregory Scalia ( ; March 11, 1936 – February 13, 2016) was an Associate Justice of the Supreme Court of the United States from 1986 until his death in 2016.
Gregory