About
John W. Dennehy is a seasoned trial attorney and the Managing Partner of Dennehy Law. His practice encompasses business litigation, civil litigation, construction law, corporate law, employment law, and insurance law. With a wealth of experience, he has successfully represented professionals, business owners, and individuals in complex litigation matters. His career includes significant roles at Donovan Hatem LLP and Devine, Millimet & Branch, where he led major litigation teams. A former U.S. Marine, John brings discipline and tenacity to every case he handles.
John earned his Juris Doctor from Suffolk University Law School and his Bachelor of Arts from the University of North Carolina Wilmington. He is also a graduate of Pinkerton Academy. Further enhancing his legal expertise, he is a Chartered Property & Casualty Underwriter, bringing valuable insight into insurance-related disputes. His extensive legal background has positioned him as a leader in trial advocacy, earning favorable verdicts and settlements for clients across various industries.
John has litigated cases involving high-rise buildings, hospitals, universities, manufacturing plants, bridges, tax issues, and real estate transfers. He has successfully handled high-exposure personal injury cases, including wrongful death, traumatic brain injury, quadriplegia, and amputation claims. Additionally, he has represented clients in business disputes, hedge fund litigation, copyright and trademark violations, trade secret conflicts, and complex commercial contracts. With extensive trial experience, John frequently appears in New Hampshire and Massachusetts state and federal courts, securing victories in jury trials, administrative hearings, mediations, and arbitrations.
Licensed in New Hampshire, Massachusetts, the U.S. District Courts of NH and MA, and the First Circuit Court of Appeals, John is an active member of legal associations, including the New Hampshire Bar Association, Massachusetts Bar Association, and Boston Bar Association. His dedication extends to community service, where he has served as a church moderator, youth sports coach, and corporate officer for a nonprofit.
John W. Dennehy is a relentless advocate for his clients, offering strategic and results-driven representation in complex litigation matters.
Law Office Affiliations
- Managing Partner, Dennehy Law
- Member, Rockingham County Bar Association
- Member, New Hampshire Bar Association
- Member, Boston Bar Association
- Member, Massachusetts Bar Association
- Member, Charted Property & Casualty Underwriters Society
Licensed State
- New Hampshire
- Massachusetts
Education
- Suffolk University Law School
Juris Doctor (JD) - University of North Carolina Wilmington
Bachelor of Arts (BA)
Awards & Badges




- Construction and development
- Copyright infringement
- Corporate and incorporation
- Insurance
- Partnership
- Trademark infringement
- Wrongful death