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Dennis Duncan, Dennis

Dennis Duncan

Zimmer, Duncan & Cole
Parker, SD
(605) 297-4446


  • University of South Dakota
    B.A. in Government - 1970
    Minors:  History and English
  • University of South Dakota
    Juris Doctorate 1973

Professional Experience

Following graduation from the University of South Dakota School of Law in 1973 and a clerkship with the South Dakota Supreme Court, Dennis Duncan joined John Zimmer in the practice of law in Parker, South Dakota in 1974.

While the focus of his legal practice was litigation, he also began to serve as a registered lobbyist with the South Dakota Legislature.  Over the years, the legal practice has evolved to become more focused on representing corporate and individual clients with issues before agencies and departments of the state and federal government and insurance litigation.  A major portion of time is spent advising corporate and individual clients relative to their relations with state government, including government procurement, agency rule making and agency regulation of businesses and occupational licensing.

Representing the interests of national clients such as the Pharmaceutical Research and Manufacturers of America, Eli Lilly, Verizon Wireless, Allstate Insurance Company, TransCanada Corporation or state-based clients such as Heartland Consumers Power District, South Dakota Association of Mutual Insurance Companies, South Dakota Collectors Association, South Dakota Insurance Alliance, South Dakota Library Association and the University of South Dakota Alumni Association before the South Dakota Legislature has proven to become a major component of Dennis Duncan’s law practice.  Whether it be providing full-time presence for clients during the legislative session or experienced representation before state agencies and departments, Dennis Duncan can provide experienced representation gained by over thirty years of experience.

Firm members hold membership in the American League of Lobbyists and are proud to have been chosen for membership in State Law Resources and the National Association of State Lobbyists, prominent national organizations of professional governmental affairs practitioners.

It deems it important to clients to have two experienced lobbyists working for our clients, whether it be in legislature or before a state agency.

Dennis Duncan is a member of the South Dakota State Bar Association, American Bar Association, South Dakota Defense Lawyers Association, Defense Research Institute, Inc., National Health Lawyers Association, Forum Committee on Health Law - American Bar Association, Group Health Association of America, American Medical Association’s Doctor’s Advisory Network and an active member of the South Dakota State Bar having served on the Continuing Legal Education Committee, Medical - Legal Committee, and Group Benefits Committee Chairperson 1994-1998 as well as serving as a Director of the University of South Dakota Law School Foundation, Dean Search Committee for the University of South Dakota School of Law - 1993 and the Municipal Attorneys Association.

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