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Sean Carnathan

Sean Carnathan

Complex Commercial and Insurance Coverage Litigation
  • Business Law, Insurance Claims, Appeals & Appellate
  • Maine, Massachusetts, New Hampshire
Claimed Lawyer ProfileSocial Media

Sean is a partner and founder of the firm, O'Connor, Carnathan and Mack, LLC and focuses his practice in complex business litigation with a particular emphasis on insurance coverage, closely held businesses and trust and estate litigation.

Since 1993, although Massachusetts based, Sean has been litigating cases all over the country, from Texas to Minnesota and from California to Maine. He has tried or arbitrated over 25 cases in the state and federal courts of Connecticut, Delaware, Maine, Massachusetts and New Hampshire.

Sean has secured millions of dollars in recoveries for his clients. He regularly advises corporate executives in transition regarding their employment contracts and non-compete obligations.

Sean represents policyholders in disputes with their insurers. While he has substantial experience in a broad range of industries, Sean has spent years representing financial institutions such as State Street Bank and Trust Company, and investment funds such as Tuckerbrook Alternative Investments and NTV Management. Sean has a deep well of experience in real estate and construction disputes and has also represented the owners and operators of many small, closely held companies.

Sean is a regular commentator on legal issues and has published many articles throughout his career. He is the author of Massachusetts Bad Faith Insurance Litigation. The second edition of his book was published in 2020, and offers a complete guide to bad faith insurance cases under M.G. L. c. 176D. Sean is also a member of the Trial Law Institute and Diversity Law Institute of the Litigation Counsel of America. He was recently appointed a neutral at AMANDA ADR, which provides mediation and arbitration services.

Harvard Law School
LL.M. (1997) | Intellectual Property
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University of Maine School of Law
J.D. (1993) | Law
Honors: summa cum laude
Activities: Law Review, Moot Court Board, Writing Instructor
University of Maine School of Law Logo
Bowdoin College
B.A. (1986) | English Literature
Honors: magna cum laude
Activities: Rugby football club
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Professional Experience
Founder, Partner
O'Connor, Carnathan and Mack, LLC
- Current
Rubin, Hay & Gould
Associate, Junior Partner
WilmerHale (then Hale and Dorr LLP)
Securities Litigation Department
Ames Fellow
Harvard Law School
Lambert Coffin
Law Clerk
Maine Supreme Judicial Court
Articles & Publications
Massachusetts Bad Faith Insurance Litigation
Lawyers Weekly Books
Speaking Engagements
Closely Held Business Disputes: Legal Issues and Practical Considerations For Litigation and Negotiation, Boston Bar Association
Boston Bar Association
Practical Tips on Policyholder Claims for Insurer Bad Faith, Boston Bar Association
Boston Bar Association, Insurance and Tort Litigation Section
Damages, Interest and Attorneys' Fees, MCLE, 10 Winter Street, Boston, MA
Recent Updates on Close Corporations Law, Massachusetts Bar Association, 20 West Street, Boston, MA
Massachusetts Bar Association
Recurrent Discovery Issues in Insurance Bad Faith Litigation, Social Law Library, Boston, Massachusetts
Social Law Library
Chapter 176D in Commercial Litigation: When Does Liability Become Reasonably Clear?, Boston Bar Association
Boston Bar Association
Understanding Consent-to-Settle in Professional Liability Policies, Webinar
O'Connor, Carnathan and Mack
Chapter 176D Year in Review, Webinar
O'Connor, Carnathan and Mack, LLC
The Insurer's Duty to Settle Uncovered Claims, Webinar
O'Connor, Carnathan and Mack, LLC
Attorney-Client Privilege in Bad Faith Litigation: Privilege Issues From Perspectives of Policyholders and Insurers, Webinar
Irish Legal 100
Super Lawyer
Super Lawyers
Every year since 2008
Best Lawyers in America -- Trusts and Estates Litigation
U.S. News & World Report
Every year since 2016
Professional Associations
Massachusetts Bar Association
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Boston Bar Association
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Litigation Counsel of America
Senior Fellow
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Massachusetts Board of Bar Overseers
Hearing Officer
- Current
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Jurisdictions Admitted to Practice
Maine Board of Overseers of the Bar
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Massachusetts Board of Bar Overseers
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New Hampshire
New Hampshire Bar Association
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  • Free Consultation
    Initial consultation always free.
  • Credit Cards Accepted
    Visa and Mastercard
  • Contingent Fees
Practice Areas
Business Law
Business Contracts, Business Dissolution, Business Finance, Business Formation, Business Litigation, Franchising, Mergers & Acquisitions, Partnership & Shareholder Disputes
Insurance Claims
Bad Faith Insurance, Business Insurance, Disability Insurance, Health Insurance, Life Insurance, Motor Vehicle Insurance, Property Insurance
Appeals & Appellate
Civil Appeals, Federal Appeals
  • English
Websites & Blogs
O'Connor, Carnathan and Mack, LLC
O'Connor, Carnathan and Mack, LLC
Contact & Map
1 Van de Graaff Dr. Suite 104
Burlington, MA 01803
Telephone: (781) 359-9002
Fax: (781) 359-9001
Monday: 8 AM - 5 PM
Tuesday: 8 AM - 5 PM (Today)
Wednesday: 8 AM - 5 PM
Thursday: 8 AM - 5 PM
Friday: 8 AM - 5 PM
Saturday: Closed
Sunday: Closed
Notice: Fast response to email nights and weekends --