He then received his Juris Doctor degree from the Ohio State University Moritz College of Law in 1957.
[1] Slagle begin his legal career at Mudge, Stern, Baldwin and Todd in New York, New York before moving to England to serve in the U.S. Air Force Judge Advocate General Corps, where he attained the rank of captain.
He then returned to Ohio State to serve as the fourteenth Dean of the Moritz College of Law from 1974 to 1980.
Slagle then served as the President of the Law School Admission Council from 1978 to 1980 while continuing his full-time teaching at Moritz.
In 1980 Slagle was appointed the third Dean of the Florida State University College of Law and served in that role until 1984 when he returned to full-time teaching.