Mary Susan Leahy headshot
11 South Main Street
Suite 500
Concord, NH 03301
100 Arboretum Drive
Suite 140
Newington, NH 03801
Tel: 603 334 6926

Mary Susan Leahy

Of Counsel, Trusts & Estates Department

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Mary Susan is a versatile estate planning and trust attorney. In addition to advising on personal estate and tax planning issues, she also advises clients on business succession planning, having spent many years as a transactional business lawyer. Drawing on her experience as a real estate attorney, she counsels families on generational planning, such as involving ownership of lakefront and other vacation properties. She serves as a professional trustee of many private trusts and counsels charitable foundations and other tax exempt organizations.

Areas of Focus

  • Corporate Business Law
  • Estate Planning and Trust and Estate Administration
  • Probate Litigation
  • Taxation


  • New Hampshire State Courts, Maine State Courts, United States Supreme Court, United States First Circuit Court of Appeals, Federal District Court for the District of New Hampshire, United States Tax Court
  • New Hampshire Bar Association and its Sections of Elder Law and Real Property and Probate
  • Maine Bar Association, American Bar Association and its Sections of Taxation and Real Property and Probate
  • Fellow of the American College of Trust and Estate Counsel (ACTEC)
  • New Hampshire Women's Bar Association
  • AV Peer Review Rated, Martindale-Hubbell
  • Woodward/White's Best Lawyers in America® (Corporate Law, Trusts & Estates Law)
  • New England Super Lawyers® 2009
  • New Hampshire Women's Bar Associatio""s Marilla M. Ricker Achievement Award
  • Greater Concord Chamber of Commerce Citizen of the Year Award
  • Merrimack County Bar Association Lawyer of the Year Award
  • New Hampshire's Most Powerful Women Award


  • Best Lawyers in America 2020 (Corporate Law, Trusts and Estates)
  • NH Center for Nonprofits' Board Impact Award (2018)
  • Fellow, New Hampshire Bar Foundation
  • New England Super Lawyer


  • Constitutionally Speaking, Treasurer
  • New Hampshire Institute for Civics Education, Founder and Chair
  • Kennebunkport Conservation Trust, Trustee
  • Dartmouth Hitchcock's Partners for Community Wellness, Executive Committee Member
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Practice Areas

The strengths of our practice groups and the industries we serve make McLane Middleton one of the most diverse law firms in New England.

Integrity and trust

At McLane Middleton we establish and maintain long-standing relationships with our clients to help us better achieve their unique goals over time. This approach to building trust requires that our esteemed lawyers and professionals use their broad, in-depth knowledge and work together with integrity to ascertain sound resolutions to legal matters for their clients.

Strength in numbers

McLane Middleton is made up of more than 105 attorneys who represent a broad range of clients throughout the region, delivering customized solutions. As a firm we are recognized as having the highest legal ability rating. The firm is rated Preeminent by Martindale Hubbell and is recognized as one of the nation's leading law firms in Chambers USA. Our attorneys are distinguished leaders in their respective practice areas.

Meet Our People

Commitment and collaboration

McLane Middleton's versatile group of attorneys and paralegals become trusted authorities on each case through collaboration. We work with our clients to learn their individual needs first and foremost and, together, we develop comprehensive solutions to their specific legal matters. This approach helps us exceed our clients' expectations efficiently and effectively, client by client, case by case.

Practice Areas

A history of excellence

McLane Middleton was established in 1919 in New Hampshire, and has five offices across two states. However, deep historical roots don't allow you to become innate. Our firm is organized, technological, and knowledgeable. Our history means we are recognized. But our reputation is built on the highest quality of service and experience in very specific areas of law.

The Firm

Intelligence paired with action

Our team continuously seeks opportunities to enhance their professional development and put key learnings to action. The pursuit of further insight guides us to volunteer service opportunities, speaking engagements, and teaching roles. Our lawyers are sought after thought leaders across their industries, and recipients of leadership awards throughout the region.