Mr. Duffie focuses his practice on hospital law, commercial real estate transactions, zoning and municipal law. Mr. Duffie is a member of the Cumberland County Bar Association and the Pennsylvania Bar Association.
Following graduation from law school, Mr. Duffie was in the Judge Advocate General Corps, United States Army, and served as a Military Judge as part of the U.S. Army Trial Judiciary. Mr. Duffie began practicing in 1967, and following his military service, returned to the law firm in 1972 and has been a principal of the firm since 1974.

He is a past president of the Cumberland County Bar Association. He serves as general counsel for Holy Spirit Health system and as solicitor for Cumberland Valley School District. He has also served as Chairman of the Board of Managers of the West Shore YMCA and is a former member of the Board of Directors of the Greater Harrisburg Area YMCA. He is a member of St. John's Lutheran Church, Shiremanstown, where he has served as President of the Church Council and is currently a Trustee. He has served as a member of the Board of Governors, West Shore Country Club and has been active in other civic organizations.

Mr. Duffie is married to the former Linda Ann Jacobi, has three children and currently resides in Upper Allen Township.