Lon joined May & Johnson in 1980. He is the senior attorney in the Litigation Section, where his practice was devoted to civil litigation, with an emphasis on insurance defense, insurance litigation, and professional liability defense. His clients included several major insurance companies in the United States. Lon is a member of the American Board of Trial Advocates, the International Association of Defense Counsel, and the Defense Research Institute. He is the past President of the South Dakota Defense Lawyers Association and served as the South Dakota Representative to DRI.
In addition to his litigation practice, Lon has mediated over 1,100 civil disputes. He now devotes most of his practice to ADR and mediates nearly 250 disputes per year. He has successfully mediated a wide variety of civil claims, including class action lawsuits, wrongful death actions, catastrophic injury actions, medical malpractice and professional negligence claims, complex multiparty construction claims, employment/discharge claims, commercial and business disputes, including shareholder claims and first party insurance bad faith claims. As part of his neutral practice, Lon also has arbitrated numerous civil claims in various areas including nursing home liability, personal injury, wrongful death, medical malpractice, labor contracts and construction disputes.
Lon is South Dakota's charter member in the National Academy of Distinguished Neutrals, an invitation-only organization of attorneys recognized by their peers as outstanding mediators. He was named as a Great Plains Super Lawyer, as a Litigation Star in Benchmark Litigation, and was also selected for inclusion in "The Best Lawyers in America" in the area of mediation. He is a member of the American Academy of ADR Attorneys and is certified by the Academy as a mediator. He is also a member of the International Academy of Dispute Resolution and is past chairman of the South Dakota Bar Association Committee on ADR.