Sierra N. Hennessy

“Effective litigation requires a balancing act: I treat opposing counsel with professionalism and genuine respect, while advocating for my clients with a fierce, disciplined intensity that high-pressure disputes demand.” —Sierra Hennessy

Companies facing litigation that threatens their business, reputation, or financial interests turn to attorney Sierra Hennessy for practical strategy and skilled advocacy.

For clients across varied industries, including financial services, health care, hospitality, retail, media, airline, and professional sports, Sierra effectively develops and executes strategies for favorably resolving disputes in federal and state courts, before arbitration tribunals, and in proceedings before administrative law judges.

Sierra’s practice spans complex commercial litigation, business disputes, appeals, employment litigation, health care litigation, antitrust matters, intellectual property disputes, construction litigation, premises liability, and products liability claims. Whether a dispute involves a familiar issue or a highly technical subject matter, Sierra quickly learns the governing facts and law needed to mount a vigorous defense.

Litigation is complex and multifaceted, and clients look to Sierra to chart the most efficient path forward. She guides clients through every stage of a case—from initial pleadings through dispositive motions, trial, and appeal—working to resolve matters as early and efficiently as possible.

Before joining Epstein Becker Green, Sierra was a litigation attorney at a regional law firm. Previously, she practiced at an East Coast law firm, where she managed multi-party, complex construction litigation.

While in law school, Sierra interned for the Honorable Marcella Matos Wilson of the Superior Court of New Jersey, Essex County, Law Division. She also worked as a student attorney with the Seton Hall University School of Law Center for Social Justice, representing survivors of domestic violence pro bono—an experience that continues to inform her client-centered approach to litigation.

What Sierra Delivers for Clients

• Early, Cost-Effective Resolutions: Businesses looking to limit the cost and disruption of litigation benefit from Sierra’s experience securing dispositive motions, including motions to dismiss filed early in a case, which can end a dispute before it reaches costly discovery or trial.
• Advocacy in Any Forum: Sierra has tried cases to verdict, argued in arbitration hearings, and appeared before administrative law judges, giving clients continuity of counsel no matter where their dispute is venued.
• Composure in High-Profile Matters: In cases carrying significant financial exposure and public attention, Sierra remains a steady presence for her clients from the first motion through a jury’s verdict, addressing both the legal risk and the reputational stakes involved.
• Settlements That Protect the Bottom Line: When trial isn't a client’s best option, Sierra negotiates resolutions that protect their interests while preserving a workable relationship with opposing counsel—an approach that can ease what is often a long litigation process.

• The Best Lawyers in America^©: “Ones to Watch” in Commercial Litigation (2026 to 2027)

No aspect of this advertisement has been approved by the Supreme Court of New Jersey. Learn more about the award selection criteria and ranking methodology.

Education

• Seton Hall University School of Law (J.D., 2017)
  • Member, Seton Hall Legislative Journal
  • Student Bar Association Executive Board, Social Chair
  • Women's Law Forum Executive Board, Chair of Advertising and Public Relations
  • Student Attorney, Seton Hall Law Center for Social Justice
• Washburn University (B.A., magna cum laude, 2014)
  • International Dean’s List Society
  • Phi Alpha Theta National History Honor Society

Professional & Community Involvement

• New York City Ballet Young Patrons Circle