John Duncan founded the Chicago law firm Duncan Associates Attorneys and Counselors, P.C. in 2000 to concentrate on the representation of private, boutique, and traditional trust companies, family offices, and other wealth management organizations. In 2012, Duncan Associates combined with Kozusko Harris Vetter Wareh to form Kozusko Harris Duncan.

Prior to forming Duncan Associates, John headed the banking and investment practice of the international law firm Jones Day. John is a member of the Collaboration for Flourishing Families (Chair, Strategic Planning Committee) and has served as the chair for numerous committees for national and local bar associations. John is a regular contributor to professional publications including the ACTEC Journal and Trusts and Estates and a frequent speaker at legal and wealth management conferences.

John’s work with families and family offices also includes designing and implementing trans-generational family governance systems, family office risk management programs, family investment funds, and family office services platforms.

Private Asset Management named John to its “Power 25” list of prominent players in wealth management and family offices “excelling in thought leadership and levels of influence in their respective fields.”

John has worked with more than 140 ultra-wealthy families (and their advisors) on family governance and family strategic structures, including forming close to half of the regulated Private Trust Companies in the United States. John assisted a group of private trust companies in founding the PTC Association, LLC, an association of private trust companies.

John drafted a model trust company act that has now been adopted by nearly half the states. John and his firm colleagues were also the principal draftsman of the innovative trust and trust company laws enacted by New Hampshire in 2007 and 2008, which have propelled New Hampshire into the forefront of states for locating trusts and trust companies. New Hampshire’s trust laws have already served as models for trust and trust company laws adopted in Delaware, Tennessee and Nevada, and significant parts of South Dakota, Wyoming, Texas and Florida trust laws.  Other states have also adopted parts of these trust and trust company laws.

In addition, John served as principal draftsmen of the new and extremely family and family-enterprise friendly Family Trust Company Act adopted by Nevada, as well as the amendments to Nevada’s commercial trust company act.

Professional Licenses
and Designations

  • Attorney (Illinois)


  • Juris Doctor (J.D.), University of Chicago Law School
  • Bachelor of Arts (B.A.), Yale College, cum laude