Felicia H. Ellsworth


Ellsworth, Felicia H.

Felicia Ellsworth has built a distinguished portfolio of work in the Litigation/Controversy Practice Group as a member of both the Appellate & Supreme Court Litigation Group and Business Trial Group. Her trial practice focuses on complex commercial litigation in both state and federal courts and her appellate practice spans both civil and criminal matters in the state and federal appeals courts, including the Supreme Court of the United States.

Ms. Ellsworth has counseled numerous clients in commercial disputes on issues including patent infringement, trade secret misappropriation, contract law, civil procedure, real property disputes, tort law, administrative law and procedure and constitutional law. She has also counseled and represented clients in both civil and criminal appeals involving patent infringement, contract law, constitutional law and criminal law and procedure. Ms. Ellsworth has argued appeals in the First, Second, and Sixth Circuits and the Massachusetts Appeals Court.

Throughout her time at the firm, Ms. Ellsworth has become deeply involved in numerous pro bono matters. Recently and significantly, she played a lead role in the Commonwealth of Massachusetts' challenge to the constitutionality of DOMA, leading to the historic Supreme Court ruling favoring marriage equality.

Ms. Ellsworth remains involved in the fight for marriage equality nationwide, and is helping lead the firm's representation of Gay and Lesbian Advocates and Defenders in various federal courts of appeals considering marriage equality issues in the Fourth, Sixth, Seventh and Tenth Circuits.

In addition to her marriage equality pro bono representations, Ms. Ellsworth has a robust pro bono practice that includes representing individuals seeking asylum based on religious and gender persecutions and individuals appealing their criminal convictions and sentences. She is a member of the First Circuit Court of Appeals Criminal Justice Act panel, through which she provides pro bono representation to indigent defendants on appeal.

Recent Highlights

  • Led the WilmerHale team representing the State of Vermont in a matter involving the proposed relicensing of the Vermont Yankee Nuclear Power Station in administrative relicensing proceedings before the Vermont Public Service Board. The proceeding spanned approximately eighteen months and culminated in a combined five weeks of hearings in 2013.
  • Served as part of the team that successfully defended a medical device manufacturer in an appeal to the Supreme Judicial Court of Massachusetts involving damages and injunctive relief.
  • Recently presented oral argument on behalf of appellee American Honda in W&D Imports Inc. v. Lia. Five days after oral argument, the panel issued a summary order affirming the decision in American Honda's favor.
  • Recently successfully represented a client in the Supreme Court of the United States in an important case involving the intersection of the Lanham Act's prohibition on false advertising and the Federal Food, Drug, and Cosmetic Act's regulation of food and beverage labeling.
  • Served as part of the team that successfully overturned a patent infringement verdict on behalf of a major networking equipment manufacturer in the Court of Appeals for the Federal Circuit.
  • Filed several amicus curiae briefs in both the appeals courts and Supreme Court. Most recently, Ms. Ellsworth filed an amicus brief in support of certiorari on behalf of a group of Internet industry companies in Spokeo Inc. v. Robins. She has also filed amicus briefs on behalf of other individual clients and groups of clients in the Supreme Court and Federal Circuit addressing a variety of different topics.     
  • Helped lead a team of WilmerHale lawyers that began representing the Commonwealth of Massachusetts in 2009 as co-counsel in its challenge to the constitutionality of DOMA, the first in the nation. Both the District of Massachusetts and the First Circuit struck down DOMA as unconstitutional—marking the first ruling by a federal appeals court striking down DOMA. These decisions were later confirmed by the Supreme Court's decision in United States v. Windsor. In the Windsor case, Ms. Ellsworth once again helped lead a WilmerHale team in filing an amicus brief on behalf of more than a dozen former Solicitors General of the United States, White House Counsel, and heads of the Office of Legal Counsel explaining that the Supreme Court has jurisdiction to hear a case challenging DOMA even though the federal government did not defend the law. The Court's jurisdictional ruling was essential to its ultimate decision to strike down DOMA.
  • Helped lead the WilmerHale team in filing a brief in Hollingsworth v. Perry, challenging the constitutionality of California's Proposition 8, on behalf of more than 100 prominent Republicans, including top advisers to former President George W. Bush, seven former governors, and 12 current and former members of Congress. The brief received significant media attention that included coverage by The Wall Street Journal, National Law Journal and Law360.

Professional Activities

Ms. Ellsworth is admitted to practice in the Commonwealth of Massachusetts and before the United States District Court for the District of Massachusetts, the United States Courts of Appeals for the First, Second, Sixth, Tenth, and Federal Circuits, and the Supreme Court of the United States. She is also a member of the Boston Bar Association and the Women’s Bar Association.


Ms. Ellsworth served as a Special District Attorney in the Middlesex District Attorney's Office from November 2010-April 2011, where she prosecuted cases involving violent crimes, financial fraud, and many other offenses. Previously, Ms. Ellsworth served as a law clerk to Chief Justice John G. Roberts, Jr. of the Supreme Court of the United States, and then-Chief Judge Michael Boudin of the United States Court of Appeals for the First Circuit. During law school, Ms. Ellsworth served as editor-in-chief of The University of Chicago Law Review and interned with the United States Attorney's Office for the District of Massachusetts.

Publications & News


December 31, 2014

Direct-to-Consumer Wine Shipment Comes to Massachusetts on January 1

This holiday season brings an extra reason to celebrate for Massachusetts wine enthusiasts.

June 17, 2014

US Supreme Court Issues Unanimous Ruling in Favor of WilmerHale Client POM Wonderful

On June 12, 2014, the US Supreme Court ruled unanimously in favor of WilmerHale client POM Wonderful LLC (POM) in an important case involving the intersection of the Lanham Act’s prohibition on false advertising and the Federal Food, Drug, and Cosmetic Act's (FDCA) regulation of food and beverage labeling.

January 6, 2014

WilmerHale Announces the Elevation of Partners and Special Counsel

We are pleased to announce the elevation of our new partners and special counsel.

June 26, 2013

WilmerHale Plays Key Role in Historic Supreme Court Ruling Favoring Marriage Equality

June 1, 2012

First Circuit Holds DOMA Unconstitutional

April 27, 2010

WilmerHale Wins Fifth Case in the Federal Circuit in Two Weeks

December 11, 2008

Massachusetts Releases Proposed Pharmaceutical and Medical Device Manufacturer Code of Conduct

October 30, 2008

Federal Circuit Decision in In re Bilski Has Far-Reaching Implications

August 13, 2008

Note on Comparative Treatment of Business Method and Software Patents in the United States and European Union

Co-authored with Robert C. Pozen, Harvard Business School Note 309-023.

January 1, 2004

Comment, Worst Seats in the House: Stadium-Style Movie Theaters and the Americans with Disabilities Act, 71 U. Chi. L. Rev. 1109


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JD, High Honors, University of Chicago Law School, 2005, Order of the Coif; Editor-in-Chief, The University of Chicago Law Review

BS, Foreign Service, cum laude, Georgetown University, School of Foreign Service, 2000, Honors Certificate in Muslim-Christian Understanding

Bar Admissions



The Hon. Michael Boudin, US Court of Appeals for the First Circuit, 2005 - 2006

The Hon. John G. Roberts, Jr., US Supreme Court, 2006 - 2007