Brian E. O’Neill


Brian E. O’Neill is an accomplished trial and appellate attorney with first-chair experience in the Delaware Court of Chancery, as well as the federal and state courts throughout Pennsylvania and Delaware. He has tried over one hundred cases to verdict, winning on behalf of plaintiffs and defendants.

Brian E. O’Neill

Legal Experience That Stands Out

Brian represents corporations, LLCs, partnerships, directors, officers, and business owners in complex litigation in Delaware and Pennsylvania state and federal courts.

Brian serves as counsel to corporations and their directors and officers in litigation arising from deadlocked boards, contested director elections and officer appointments, and breach of fiduciary duty claims. He also represents stockholders, partners, and LLC members in dissolution proceedings, books and records actions, advancement litigation, and earn-out disputes.

Brian also routinely represents commercial and residential property owners in tax assessment appeal litigation. He has obtained millions of dollars in tax reductions on behalf of his clients collectively over the past twenty years. Brian also defends property owners against tax appeals filed by taxing authorities.

Brian is active in his community as a little league baseball coach and volunteer on behalf of non-profit organizations.

Representative Matters

Lead trial counsel in the Delaware Court of Chancery for a municipality in an action to compel a countywide property tax reassessment based upon non-uniformity under the Delaware State Constitution. Case of first impression under Delaware law whether a municipality has standing to sue for a reassessment. Favorable ruling after the liability phase of trial. Countywide reassessment ordered. In re Delaware Public Schools Litigation, 239 A.3d 451 (Del. Ch. 2020).

Lead counsel for a former Mayor of Wilmington in defense of a Section 1983 action involving death and injuries to municipal firefighters. Obtained dismissal of the Complaint in the U.S. District Court of Delaware. Speakman, et al. v. Williams, et al., 2019 WL 4751939 (D. De. Sept. 30, 2019). Dismissal affirmed on appeal to the Third Circuit Court of Appeals. 2021 WL 49947 (3d. Cir. Jan. 6, 2021).

Successful defense of a commercial property owner in Montgomery County, Pennsylvania from a challenge by a school district to increase the property tax assessment from $22 million to $38 million.

Lead counsel in a Section 226 action for five individual directors of a Delaware corporation seeking the appointment of a custodian by the Delaware Court of Chancery to break a deadlock among the ten board members. The action settled favorably after positive pre-trial rulings from the Court.

Lead counsel in a Section 225 action in the Delaware Court of Chancery defending five managers/directors of a Delaware limited liability company from a challenge to their status as duly elected managers. Action resolved in clients’ favor following positive pre-trial rulings and aggressive discovery strategy.

Successfully sued a foreign corporation and U.S. based advisors for defrauding U.S. based investors in breach of contract and fraud action in the U.S. District Court for the Eastern District of Pennsylvania. Action settled following favorable rulings on summary judgment motions.

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Georgetown University Law Center
LL.M. Securities and Financial Regulation, 2013

Boston University School of Law
J.D., magna cum laude, 1996

University of Pennsylvania
B.A., 1993

Bar Admissions

New Jersey

U.S. Court of Appeals for the Third Circuit
U.S. District Court for the Eastern District of Pennsylvania
U.S. District Court for the District of Delaware
U.S. District Court for the District of New Jersey