Jonathan (Jack) O'Neil

Associate

I'm a 2026 Nixon Peabody Pro Bono Champion.Read more about our Pro Bono program

Jack O’Neil is an associate in Nixon Peabody’s Complex Commercial Disputes group. He represents entities and individuals in a wide variety of disputes and litigation.

Practice Areas

Complex Disputes Litigation

My focus

My practice focuses on complex litigation matters. I represent clients in various phases of litigation, from conducting in-depth legal research and drafting memoranda for motions to discovery and trial preparation.

Prior to joining Nixon Peabody, I served as a judicial law clerk for the New Hampshire Superior Court, where I drafted court orders for motions concerning injunctions, land use appeals, dismissal of claims, summary judgment, discovery disputes, and admissibility of evidence. I worked closely with judges and fellow law clerks to untangle complex legal issues.

Looking ahead

I have been following developments in the application and scope of the sovereign immunity doctrine.

In the news

340B Report
Second hospital sues Lilly for cutting off 340B pricing
This article covers a lawsuit NP filed on behalf of New Hampshire’s Mary Hitchcock Memorial Hospital against Eli Lilly, challenging the drug company’s decision to cut off the hospital from 340B pricing on prescription drugs. Boston Complex Disputes partner Morgan Nighan leads the NP team, which also includes Washington, DC partner Brian Whittaker, Manchester partner Nate Warecki and associate Jack O’Neil, Los Angeles associate Jonathan Assia, and paralegal Grace Geiser, all of the Complex Disputes practice, as well as senior eDiscovery specialist Alicia Do and summer associate Caroline Sharis.
July 30, 2026
Bloomberg Law
New Hampshire hospital sues Lilly over demands under drug plan
This article mentions NP for representing New Hampshire’s Mary Hitchcock Memorial Hospital in its lawsuit against Eli Lilly, challenging the drug company’s decision to cut off the hospital from 340B pricing on prescription drugs. Boston Complex Disputes partner Morgan Nighan leads the NP team, which also includes Washington, DC partner Brian Whittaker, Manchester partner Nate Warecki and associate Jack O’Neil, Los Angeles associate Jonathan Assia, and paralegal Grace Geiser, all of the Complex Disputes practice, as well as senior eDiscovery specialist Alicia Do and summer associate Caroline Sharis.
July 28, 2026

Admitted to practice

New Hampshire

Education

Boston University School of Law, JD
University of Pennsylvania, BA

Professionals in the Practice Area

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John Ruskusky
Partner / Practice Group Leader, Complex Disputes
- Chicago
- Chicago +1 312.977.4460
- Mobile +1 708.606.8720
- jtruskusky@nixonpeabody.com
Daniel J. Hurteau
Office Managing Partner / Deputy Practice Group Leader, Complex Disputes
- Albany
- Albany +1 518.427.2652
- New York City +1 212.940.3020
- dhurteau@nixonpeabody.com
Joseph J. Ortego
Partner / Chair, NP Trial / Leader, Aviation
- New York City
- New York City +1 212.940.3045
- jortego@nixonpeabody.com
Carolyn G. Nussbaum
Retired Partner
- Rochester
- Rochester +1 585.263.1558
- Mobile +1 585.766.1480
- cnussbaum@nixonpeabody.com
Christopher M. Mason
Partner / Deputy Leader, Class Actions & Aggregate Litigation / Leader, Arbitration Team
- New York City
- New York City +1 212.940.3017
- cmason@nixonpeabody.com