John was born in Missoula and grew up in Helena. He earned a bachelor's degree in philosophy, magna cum laude, from Carroll College in 1969, and received his Juris Doctor degree with high honors from the University of Montana School of Law in 1973. He accepted two federal clerkships after law school, and clerked for U.S. District Judge W.J. Jameson from 1973-1974, and for U.S. Circuit Judge James R. Browning, Ninth Circuit, from 1974-1975. John was admitted to practice in both state and federal courts in Montana in 1973, and is also admitted to the U.S. Court of Appeals for the Ninth Circuit.

John has been in private practice for 33 years, and is a founding member of Hughes, Kellner, Sullivan & Alke. His practice areas include employment law, mediation, design professional defense, health care, and civil litigation. He holds an AV rating, the highest rating in the Martindale Hubbell Law Directory, and is also listed in Band One of Montana Employment Lawyers by Chambers and Partners, and in the Labor and Employment Section of The Best Lawyers in America. He is a member of the State Bar of Montana, the American Judicature Society, the Defense Research Institute, and the Montana Defense Trial Lawyers Association. John's hobbies and interests include hiking, photography, yoga, and gardening.