Nicholas R. Parrillo

William K. Townsend Professor of Law, Yale Law School

Biography

Nicholas R. Parrillo is Townsend Professor of Law at Yale, with a secondary appointment as Professor of History. His research and teaching focus on administrative law and government bureaucracy and extend to legal history, remedies, and legislation. He has received the ABA’s award for the year’s best scholarship in administrative law and the Law and Society Association’s Hurst Prize for the year’s best book in legal history.

Parrillo’s Yale Law Journal article finding new originalist evidence of broad congressional delegations to agencies was discussed in the Solicitor General’s winning brief in the Supreme Court’s latest nondelegation case and in the en banc 5th Circuit opinion in that case. His Harvard Law Review article on how the judiciary handles the federal government’s disobedience to court orders has been discussed in The Washington Post, The Wall Street Journal, and The New York Times. Parrillo also authored a study that provided the empirical basis for best practices adopted by the Administrative Conference of the United States (ACUS) on the federal government’s ubiquitous but controversial use of guidance documents. Peer scholars at Jotwell, in selecting the “best new scholarship” in law, selected each of these three publications (one of them twice). Parrillo’s most recent article, invited for GW’s annual administrative law issue, reveals and analyzes dramatic variation among industries in their willingness to sue their federal health-and-safety regulators.

Parrillo has testified before Congress, been quoted by the Supreme Court, is a senior fellow of ACUS, and has been an instructor at the New York Historical Society’s graduate institute and an invited speaker before the 2nd Circuit Judicial Conference, the U.S. Department of Justice (in 2019 and again in 2024), the ACLU’s national legal staff, and the Federalist Society’s national convention (two times). He is a recipient of the Law School’s annual teaching award.

Sean Lev

Partner, Harris, Wiltshire & Grannis LLP

Biography

Sean Lev, a former General Counsel of the FCC and acting General Counsel of the Department of Energy, advises and advocates in both courts and agencies for clients with complex regulatory problems in technology, energy, and other fields.
He serves as chair of HWG’s Energy Practice and co-chair of the Issues and Appeals Practice.

Sean has more than 30 years of experience helping clients in the public, private, and non-profit sector solve problems involving critical issues of administrative law. He has argued scores of cases in federal and state appellate and trial courts both supporting and challenging agency decisions and has advised Cabinet Secretaries, three FCC Chairs, sophisticated regulated companies, and numerous non-profits and individuals.

As General Counsel of the Federal Communications Commission, Sean was responsible for all legal advice provided to the FCC Chair and Commissioners and oversaw all FCC litigation. Sean was also heavily involved in the Commission’s review of major transactions and enforcement activity. Prior to being named General Counsel, Sean served as Deputy General Counsel and Senior Advisor to the Chairman.

Before joining the FCC, Sean was designated by President Obama to serve as the Acting General Counsel of the United States Department of Energy (DOE). In that role, he was the chief legal officer for the Department, and provided advice on the full range of issues relevant to its mission, including those involving energy efficiency standards, nuclear energy, oil and gas, environmental remediation, and national security. Sean also served as the Deputy General Counsel for Environment and Nuclear Programs at DOE. In that role, he led the agency’s litigation before the Nuclear Regulatory Commission and served as the lead agency lawyer in resolving major environmental and other disputes.

Sean most recently served as Legal Director of Democracy Forward, a public interest nonprofit dedicated to furthering the rule of law and fighting unlawful agency decision making. In this role, he oversaw a team of more than a dozen litigators and supervised numerous successful legal challenges against federal agencies and state and local governments.

Sean has significant experience advising clients in private practice, having spent more than fifteen years as a partner of a major Washington, DC based law firm. During that time, Sean had leading roles in numerous key cases involving technology law and policy and in advocating on regulatory and litigation issues raised by major industry transactions.

He started his legal career as an Honors Program attorney on the Civil Division, Appellate Staff at the United States Department of Justice and as a clerk to the Honorable Patricia M. Wald of the U.S. Court of Appeals for the District of Columbia Circuit.

Nicholas R. Parrillo

William K. Townsend Professor of Law, Yale Law School

Biography

Nicholas R. Parrillo is Townsend Professor of Law at Yale, with a secondary appointment as Professor of History. His research and teaching focus on administrative law and government bureaucracy and extend to legal history, remedies, and legislation. He has received the ABA’s award for the year’s best scholarship in administrative law and the Law and Society Association’s Hurst Prize for the year’s best book in legal history.

Parrillo’s Yale Law Journal article finding new originalist evidence of broad congressional delegations to agencies was discussed in the Solicitor General’s winning brief in the Supreme Court’s latest nondelegation case and in the en banc 5th Circuit opinion in that case. His Harvard Law Review article on how the judiciary handles the federal government’s disobedience to court orders has been discussed in The Washington Post, The Wall Street Journal, and The New York Times. Parrillo also authored a study that provided the empirical basis for best practices adopted by the Administrative Conference of the United States (ACUS) on the federal government’s ubiquitous but controversial use of guidance documents. Peer scholars at Jotwell, in selecting the “best new scholarship” in law, selected each of these three publications (one of them twice). Parrillo’s most recent article, invited for GW’s annual administrative law issue, reveals and analyzes dramatic variation among industries in their willingness to sue their federal health-and-safety regulators.

Parrillo has testified before Congress, been quoted by the Supreme Court, is a senior fellow of ACUS, and has been an instructor at the New York Historical Society’s graduate institute and an invited speaker before the 2nd Circuit Judicial Conference, the U.S. Department of Justice (in 2019 and again in 2024), the ACLU’s national legal staff, and the Federalist Society’s national convention (two times). He is a recipient of the Law School’s annual teaching award.

Jenn L. Mascott

Judge, U.S. Court of Appeals for the Third Circuit

Biography

Hon. Jennifer Mascott served as Associate Professor of Law and Director of the Separation of Powers Institute at The Catholic University of America’s Columbus School of Law before her appointment to the federal bench. On July 16, 2025, President Donald J. Trump nominated her to the U.S. Court of Appeals for the Third Circuit (Delaware), and she was confirmed on October 9, 2025.

Prior to her confirmation, Judge Mascott wrote extensively in administrative and constitutional law, statutory interpretation, and the separation of powers. Her scholarship—published in leading journals including the Stanford Law Review, Notre Dame Law Review, and Supreme Court Review—was cited by the U.S. Supreme Court and multiple federal courts. She also contributed Supreme Court commentary for NBC Universal.

Before joining Catholic Law, she was an Assistant Professor and Co-Director of The C. Boyden Gray Center at George Mason University’s Antonin Scalia Law School. In 2022 she became co-author of Beermann, Cass & Diver’s Administrative Law: Cases and Materials (9th ed.). In 2023 she received the Justice Joseph Story Award for excellence in scholarship, teaching, and advancing the rule of law.

Judge Mascott also served as a Council Member of the ABA’s Administrative Law Section and as a Public Member of the Administrative Conference of the United States. She frequently testified before Congress on executive power, regulatory reform, and judicial jurisdiction, and participated in multiple Supreme Court confirmation hearings.

From 2019 to 2021, she took leave from academia to serve as Deputy Assistant Attorney General in the Department of Justice’s Office of Legal Counsel and later as Associate Deputy Attorney General, where she argued federal cases and assisted with Justice Amy Coney Barrett’s confirmation. Earlier in her career, she clerked for Justice Clarence Thomas and for then-Judge Brett M. Kavanaugh on the D.C. Circuit.

Judge Mascott earned her J.D. summa cum laude from the George Washington University Law School and her B.A. from the same institution.

Nicholas R. Parrillo

William K. Townsend Professor of Law, Yale Law School

Biography

Nicholas R. Parrillo is Townsend Professor of Law at Yale, with a secondary appointment as Professor of History. His research and teaching focus on administrative law and government bureaucracy and extend to legal history, remedies, and legislation. He has received the ABA’s award for the year’s best scholarship in administrative law and the Law and Society Association’s Hurst Prize for the year’s best book in legal history.

Parrillo’s Yale Law Journal article finding new originalist evidence of broad congressional delegations to agencies was discussed in the Solicitor General’s winning brief in the Supreme Court’s latest nondelegation case and in the en banc 5th Circuit opinion in that case. His Harvard Law Review article on how the judiciary handles the federal government’s disobedience to court orders has been discussed in The Washington Post, The Wall Street Journal, and The New York Times. Parrillo also authored a study that provided the empirical basis for best practices adopted by the Administrative Conference of the United States (ACUS) on the federal government’s ubiquitous but controversial use of guidance documents. Peer scholars at Jotwell, in selecting the “best new scholarship” in law, selected each of these three publications (one of them twice). Parrillo’s most recent article, invited for GW’s annual administrative law issue, reveals and analyzes dramatic variation among industries in their willingness to sue their federal health-and-safety regulators.

Parrillo has testified before Congress, been quoted by the Supreme Court, is a senior fellow of ACUS, and has been an instructor at the New York Historical Society’s graduate institute and an invited speaker before the 2nd Circuit Judicial Conference, the U.S. Department of Justice (in 2019 and again in 2024), the ACLU’s national legal staff, and the Federalist Society’s national convention (two times). He is a recipient of the Law School’s annual teaching award.

Nicholas R. Parrillo

William K. Townsend Professor of Law, Yale Law School

Biography

Nicholas R. Parrillo is Townsend Professor of Law at Yale, with a secondary appointment as Professor of History. His research and teaching focus on administrative law and government bureaucracy and extend to legal history, remedies, and legislation. He has received the ABA’s award for the year’s best scholarship in administrative law and the Law and Society Association’s Hurst Prize for the year’s best book in legal history.

Parrillo’s Yale Law Journal article finding new originalist evidence of broad congressional delegations to agencies was discussed in the Solicitor General’s winning brief in the Supreme Court’s latest nondelegation case and in the en banc 5th Circuit opinion in that case. His Harvard Law Review article on how the judiciary handles the federal government’s disobedience to court orders has been discussed in The Washington Post, The Wall Street Journal, and The New York Times. Parrillo also authored a study that provided the empirical basis for best practices adopted by the Administrative Conference of the United States (ACUS) on the federal government’s ubiquitous but controversial use of guidance documents. Peer scholars at Jotwell, in selecting the “best new scholarship” in law, selected each of these three publications (one of them twice). Parrillo’s most recent article, invited for GW’s annual administrative law issue, reveals and analyzes dramatic variation among industries in their willingness to sue their federal health-and-safety regulators.

Parrillo has testified before Congress, been quoted by the Supreme Court, is a senior fellow of ACUS, and has been an instructor at the New York Historical Society’s graduate institute and an invited speaker before the 2nd Circuit Judicial Conference, the U.S. Department of Justice (in 2019 and again in 2024), the ACLU’s national legal staff, and the Federalist Society’s national convention (two times). He is a recipient of the Law School’s annual teaching award.

James C. Ho

Judge, United States Court of Appeals, Fifth Circuit

Biography

James C. Ho is a Circuit Judge on the U.S. Court of Appeals for the Fifth Circuit. Before taking the bench on January 4, 2018, he was a partner and co-chair of the national Appellate and Constitutional Law practice group of Gibson, Dunn & Crutcher LLP.

As an appellate litigator for over a decade, including three years as the Solicitor General of Texas, Judge Ho presented 50 oral arguments in federal and state courts nationwide. He won numerous appeals, including three merits cases at the U.S. Supreme Court. He was routinely ranked among the nation’s leading lawyers by Benchmark, Chambers, Law360, The Legal 500, and The National Law Journal, among other publications. His work has been cited favorably by courts at every level of both the federal and state judiciaries. He won a Best Brief Award from the National Association of Attorneys General for every year that he served as solicitor general, and he is the only state solicitor general in history to be invited by the U.S. Supreme Court to express the views of a state.

Judge Ho has served in all three branches of the federal government. On the Senate Judiciary Committee, he served as chief counsel of the Subcommittees on the Constitution and Immigration under Senator John Cornyn. At the Justice Department, he served as Special Assistant to the Assistant Attorney General for Civil Rights and an attorney-advisor at the Office of Legal Counsel. He clerked for Judge Jerry E. Smith of the U.S. Court of Appeals for the Fifth Circuit and Justice Clarence Thomas of the U.S. Supreme Court.

His record of public service also includes appointments as vice chair of the Federal Judicial Evaluation Committee in Texas and co-chair of the National Asian Pacific American Bar Association Judiciary Committee, and as a member of the U.S. Magistrate Judge Merit Selection Panel for the Northern District of Texas, the U.S. delegation to the United Nations Committee on the Elimination of Racial Discrimination, and the Continuity of Government Commission.

In addition, Judge Ho has served as an Adjunct Professor of Law at the University of Texas School of Law, where he taught seminars on U.S. Supreme Court Litigation and Religious Liberty. He has authored numerous articles in respected law reviews nationwide, including an annual feature on exemplary judicial writing for The Green Bag Almanac & Reader. He previously served as senior editor of The Green Bag and as co-editor of Pub. L. Misc.

Judge Ho graduated from Stanford University with honors and a B.A. in Public Policy in 1995, and the University of Chicago Law School with high honors in 1999. Before law school, he was a legislative aide to California State Senator Quentin Kopp. He and his wife Allyson live in Dallas, Texas, with their twin daughter and son.

Sally Katzen

Professor of Practice and Distinguished Scholar in Residence; Co-Director of the Legislative and Regulatory Process Clinic, New York University School of Law

Biography

Sally Katzen served in the Clinton administration as administrator of the Office of Information and Regulatory Affairs in the Office of Management and Budget (OMB), as deputy assistant to the president for economic policy and deputy director of the National Economic Council in the White House, and then as the deputy director for management at OMB. She served as the head of the Agency Review Group for the Obama/Biden transition with responsibility for the Executive Office of the President and all government-wide agencies. She has taught both undergraduates and at various law schools. She is a member of the American Law Institute and the National Academy of Public Administration, has served on multiple panels for the National Academy of Sciences, testified frequently before Congress, and is on the board of several non-profit organizations. Before joining the Clinton administration, Katzen was a partner in the Washington, DC, law firm of Wilmer, Cutler & Pickering, specializing in regulatory and legislative matters, while serving in leadership roles in the American Bar Association (including chair of the Section on Administrative Law and Regulatory Practice and as DC delegate to the ABA’s House of Delegates), as president of the Federal Communications Bar Association and as president of the Women’s Legal Defense Fund. She graduated from Smith College and the University of Michigan Law School, where she was the first woman editor-in-chief of the Law Review. She clerked for Judge J. Skelly Wright of the United States Court of Appeals for the District of Columbia Circuit and served in the Carter administration as the general counsel of the Council on Wage and Price Stability in the Executive Office of the President.

Nicholas R. Parrillo

William K. Townsend Professor of Law, Yale Law School

Biography

Nicholas R. Parrillo is Townsend Professor of Law at Yale, with a secondary appointment as Professor of History. His research and teaching focus on administrative law and government bureaucracy and extend to legal history, remedies, and legislation. He has received the ABA’s award for the year’s best scholarship in administrative law and the Law and Society Association’s Hurst Prize for the year’s best book in legal history.

Parrillo’s Yale Law Journal article finding new originalist evidence of broad congressional delegations to agencies was discussed in the Solicitor General’s winning brief in the Supreme Court’s latest nondelegation case and in the en banc 5th Circuit opinion in that case. His Harvard Law Review article on how the judiciary handles the federal government’s disobedience to court orders has been discussed in The Washington Post, The Wall Street Journal, and The New York Times. Parrillo also authored a study that provided the empirical basis for best practices adopted by the Administrative Conference of the United States (ACUS) on the federal government’s ubiquitous but controversial use of guidance documents. Peer scholars at Jotwell, in selecting the “best new scholarship” in law, selected each of these three publications (one of them twice). Parrillo’s most recent article, invited for GW’s annual administrative law issue, reveals and analyzes dramatic variation among industries in their willingness to sue their federal health-and-safety regulators.

Parrillo has testified before Congress, been quoted by the Supreme Court, is a senior fellow of ACUS, and has been an instructor at the New York Historical Society’s graduate institute and an invited speaker before the 2nd Circuit Judicial Conference, the U.S. Department of Justice (in 2019 and again in 2024), the ACLU’s national legal staff, and the Federalist Society’s national convention (two times). He is a recipient of the Law School’s annual teaching award.