Before joining with Frank L. Gallucci III to form Plevin & Gallucci in 2005, he served as a partner with a respected plaintiff litigation firm in Cleveland for over 50 years. He was repeatedly recognized by his peers as one of the 100 Outstanding Lawyers by Inside Business Magazine and named a Super Lawyer®. While at Plevin & Gallucci, he was selected as a Top 10 Lawyer in Ohio by Super Lawyers.

Leon was a member of the Cleveland Bar Association, the Cuyahoga County Bar Association and the American Bar Association. He served on a number of legal boards and committees, including the American Arbitrators Association and the Board of Bar Examiners of the Supreme Court of Ohio, and served as President of the Cleveland-Marshall College of Law Alumni Association. He was a member and Chairman of the Cleveland Regional Advisory Council of the American Arbitration Association and a trustee of the Cleveland Academy of Trial Lawyers. He also was a founding Life Member of the Eighth District Court of Appeals.

A prominent community leader in Northeast Ohio, Leon was President of the Cleveland Artists Foundation, a trustee of the Cleveland State University Development Foundation, the Cleveland Rape Crisis Center and the Citizens League, as well as a member of the Board of Directors of the Beck Center for the Performing Arts.

He received his undergraduate degree from West Virginia University and his law degree from The Cleveland-Marshall College of Law. When he passed away in 2008, he left a legacy of legal and civic leadership in Northeast Ohio that remains without equal.