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 high-stakes 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 represented numerous clients in commercial disputes on issues including antitrust matters, contract law, real property disputes, tort law, administrative law and procedure, and constitutional law. She has also represented clients in both civil and criminal appeals involving patent infringement, contract law, constitutional law, and criminal law and procedure. Ms. Ellsworth has represented clients in administrative tribunals; in state trial and appellate courts, including the Supreme Judicial Court; in federal district courts; in the United States Courts of Appeals for the First, Second, Fourth, Fifth, Sixth, Ninth, Tenth and Federal Circuits; and in the Supreme Court of the United States. She has argued before both federal and state appeals courts, including the First, Second, and Sixth Circuits and the Massachusetts Appeals Court.

As co-chair of the firm's Pro Bono and Community Service Committee, Ms. Ellsworth also maintains a robust pro bono practice, including representing clients in constitutional cases, criminal appeals, immigration proceedings and civil rights actions. 

Recent Highlights

  • Defending against putative class action lawsuits in federal and state court arising out of a recent highly publicized data breach. 
  • Representing multinational networking equipment manufacturer in a patent infringement appeal in the Federal Circuit and Supreme Court, in a case argued in the Supreme Court in March 2015. 
  • Helping to lead the WilmerHale team in filing a brief in Obergefell v. Hodges, concerning government recognition of the freedom to marry, on behalf of a total of 303 Republican, libertarian, conservative and center-right high-profile activists and government officials, including past presidential candidates, seven current and former governors, and 23 current and former members of the House of Representatives and US Senate. The brief received significant media attention when filed.
  • Representing a private beverage company in the Ninth Circuit and Supreme Court in an important Lanham Act case, resulting in a unanimous ruling in the client's favor in a case that attracted significant press coverage, including in The New York Times and Law360.
  • Helping to lead the WilmerHale team in filing amicus briefs on behalf of Gay & Lesbian Advocates & Defenders in the Fourth, Fifth, Sixth, Seventh, and Tenth Circuits in appeals arising out of challenges to same-sex marriages bans in several states. Ms. Ellsworth and the team have argued that these bans cannot survive rational-basis review because the proffered rationales for the ban either lack a rational connection to the bans or are based on illegitimate purposes, or both.
  • Representing a multi-national oil and gas company in several matters as part of a litigation in which tens of billions of dollars in damages are sought from energy industry companies based on allegations that oil and gas development work over many decades has damaged coast property in Louisiana and made it more vulnerable to flood damage.
  • Leading 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 18 months and culminated in a combined five weeks of hearings in 2013.
  • Representing a medical device manufacturer in a successful appeal to the Supreme Judicial Court of Massachusetts involving damages and injunctive relief.
  • Presenting 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. 
  • Filing numerous amicus curiae briefs in both in the Supreme Court, Federal Circuit and other courts of appeals addressing a variety of different topics. 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.    


Honors & Awards

  • Named to the Massachusetts Lawyers Weekly 2017 Top Women of Law list
  • Named to the "Top Women Attorneys in Massachusetts Rising Stars" list in the April 2016 issue of Boston Magazine
  • Named a 2016 Trial Rising Star by Law360, a recognition that honors only five attorneys nationwide for their professional accomplishments
  • Recognized as an "Up & Coming Lawyer" by Massachusetts Lawyers Weekly in its 2015 Excellence in the Law edition
  • Named a "Massachusetts Super Lawyers' Rising Star" in 2015 and 2016 in the area of appellate and Supreme Court litigation

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. In 2017, she was appointed by the Justices of the Supreme Judicial Court of Massachusetts to the Standing Advisory Committee on Rules of Civil and Appellate Procedure for the Massachusetts Court System. She is a member of the Board of Trustees of the Women’s Bar Foundation, and is 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


November 3, 2017

Massachusetts Lawyers Weekly Recognizes Felicia Ellsworth as a Top Woman of Law

Massachusetts Lawyers Weekly has included Felicia Ellsworth on its annual Top Women of Law list—an award that honors outstanding women lawyers whose contributions are invaluable to the legal profession.

August 29, 2017

Felicia Ellsworth Appointed to Standing Advisory Committee on Rules of Civil and Appellate Procedure

The committee reviews issues and proposals concerning the Massachusetts Rules of Civil and Appellate Procedure, and advises the Justices on the rules of civil and appellate procedure.

April 22, 2016

Felicia Ellsworth Named a Trial Rising Star by Law360

WilmerHale Partner Felicia Ellsworth is one of only five attorneys nationwide named a 2016 Trial Rising Star by Law360. This annual competition honors the top legal talent under 40 years old.

December 31, 2015

Federal Circuit Reversed $74M Judgment in Favor of Cisco

On December 28, 2015, WilmerHale achieved a significant victory for Cisco Systems, when a panel of the Federal Circuit unanimously reversed a $74 million judgment against Cisco after concluding that plaintiff Commil USA, LLC had failed to prove at trial that Cisco's products actually infringe Commil's patent.

May 21, 2015

Felicia Ellsworth Recognized Among Massachusetts Lawyers Weekly Up & Coming Lawyers

Massachusetts Lawyers Weekly has recognized Partner Felicia Ellsworth in its 2015 Excellence in the Law edition.

March 8, 2015

Leading Boston Law Firms Join Forces to Challenge Public Charter School Cap, Ensure Students' Rights

In an unprecedented joint legal effort, three leading Boston law firms—WilmerHale, Goodwin Procter, and Foley Hoag—announced this morning that they plan to file a pro bono lawsuit on behalf of Boston school students to lift the state's cap on public charter schools and ensure every student's constitutional right to an adequate education.

March 6, 2015

303 Conservatives File Historic Amicus Brief in Marriage Equality Case Before US Supreme Court

Project Right Side and former RNC Chairman Ken Mehlman formally filed an amicus brief with the United States Supreme Court involving four landmark cases slated to be heard on April 28, 2015 concerning government recognition of the freedom to marry.

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.

November 20, 2014

Prominent Lawyers Publish Essay Defining and Shaping Ethical Responsibilities of Lawyers

Harvard Law School's Center on the Legal Profession and Wilmer Cutler Pickering Hale and Dorr LLP are pleased to announce the publication of an essay calling for lawyers, as professionals and as citizens, to balance concerns about the current economic transformation of lawyering with a strong commitment to four ethical responsibilities: to clients/stakeholders, the legal system, their own institution and society. The essay is co-authored by three internationally renowned lawyers representing corporate, law firm and academic environments.

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.

Pro Bono and Community Involvement

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.


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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

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