Sam Callahan | People | Arnold & Porter

Sam Callahan, former Senior Counsel of the White House Office of Management and Budget (OMB), represents businesses, trade associations, nonprofit organizations, and public officials in complex litigation involving federal agency action. His practice focuses on administrative law and regulatory disputes, including challenges under the Administrative Procedure Act (APA), constitutional constraints on executive authority, and federal appropriations and funding issues.

A member of the firm’s administrative law and appellate teams, Sam litigates significant matters at every level of the federal judiciary and provides strategic counsel to clients facing high-stakes federal investigations, negotiations, and other executive actions. He is a co-founder and editor of the firm’s Major Questions blog and frequently presents on developments in administrative law.

At OMB, Sam supervised APA litigation and was a principal legal advisor to the Office of Information and Regulatory Affairs (OIRA). In that role, he worked closely with senior White House officials, agency general counsel, and the Department of Justice on the development and defense of significant regulatory initiatives. He contributed to government-wide strategy on cross-cutting administrative law issues, including the major questions doctrine, the Congressional Review Act, and the implications of the Supreme Court’s decision in Loper Bright Enterprises v. Raimondo. Sam also advised on matters involving presidential authority, fiscal and appropriations law, and congressional oversight. That work included overseeing OMB’s AI docket, including through legal review of the Biden Administration’s AI executive orders, national security memoranda, and related interagency guidance.

Sam clerked for Judge Paul V. Niemeyer of the U.S. Court of Appeals for the Fourth Circuit and Judge Christopher R. Cooper of the U.S. District Court for the District of Columbia. He graduated magna cum laude from Harvard Law School, where he was an Executive Editor of the Harvard Law Review, and received degrees in economics and trumpet performance from Indiana University. He remains active in music as a member of the Capital City Symphony and as a grants panelist for the National Endowment for the Arts.

Focus Areas

Experience

Major nonprofit organizations in advising on litigation strategy and novel regulatory issues related to threatened revocations of tax-exempt status under section 501(c)(3) of the Internal Revenue Code.
Pharmaceutical manufacturers and trade associations on numerous constitutional, statutory, and administrative law issues, including federal government efforts to impose most-favored-nation (MFN) prescription drug pricing.
AT&T in several state regulatory proceedings.
Public media broadcasting stations on Federal Communications Commission compliance and policy issues.
Foreign-aid grantees and contractors in litigation challenging funding freezes by the U.S. Agency for International Development (USAID) and Department of State.

National trade association in successful APA challenge to novel emissions and fuel-consumption regulations imposed on trailers. Persuaded the D.C. Circuit to stay enforcement and vacate the agencies’ rules as exceeding their statutory authority. Truck Trailer Manufacturers Ass’n v. EPA, 17 F.4th 1198 (D.C. Cir. 2021).
Property developer in successful appeal regarding an agency’s application of historic preservation law to a major redevelopment project. D.C. Preservation League v. Mayor’s Agent for Historic Preservation, 236 A.3d 373 (D.C. 2020).
Immigrant rights organizations at the U.S. Supreme Court in a successful APA challenge to the attempted addition of a citizenship question to 2020 Census. Department of Commerce v. New York, 139 S. Ct. 2551 (2019).

Group of over 50 companies in Third Circuit appeal involving a significant CERCLA settlement related to the Passaic River in New Jersey.
Honeywell in litigation raising complex preemption and statutory interpretation questions related to alleged radioactive emissions from the Metropolis Works uranium conversion facility.
Member of Congress in federal assault prosecution presenting issues of legislative immunity and other constitutional defenses.
Raytheon Co. in securing affirmance of dismissal of employee’s False Claims Act retaliation claims stemming from national-security-related investigation and termination. United States ex rel. Johnson v. Raytheon, 93 F.4th 776 (5th Cir. 2024).
North Carolina voters in convincing the U.S. Supreme Court to reject the “independent state legislature” theory. Moore v. Harper, 143 S. Ct. 2065 (2023).

Insurer in obtaining reversal of an $18 million judgment in the Third Circuit against an affiliate of AIG arising from faulty workmanship in the fracking of natural gas wells. American Home Assurance Co. v. Superior Well Services, Inc., 75 F.4th 184 (3d Cir. 2023).
Public health researcher in defamation action based on statements criticizing a company’s scientific research and marketing. Successfully briefed and argued Second Circuit appeal, securing dismissal on the basis that the statements were protected opinions. Valley Electronics AG v. Polis, 2022 WL 893674 (2d Cir. Mar. 28, 2022).
Healthcare company in securing affirmance of dismissal of a Clayton Act suit for failure to establish antitrust standing. Ekbatani v. Community Care Health Network, LLC, 2022 WL 31793 (11th Cir. 2022).
Former Members of Congress and House General Counsels as amici curiae in several cases at the U.S. Supreme Court and federal appellate courts involving the separation of powers, including Trump v. Mazars USA, LLP, 591 U.S. 848 (2020).
North Carolina voters and organizations in successful voting rights litigation to redraw North Carolina’s state legislative maps under state law. Common Cause v. Lewis, 2019 WL 4569584 (N.C. Super. Sep. 03, 2019).
Individual serving life sentence in briefing and arguing successful Fourth Circuit appeal asserting ineffective assistance of trial counsel. Convinced Fourth Circuit to unanimously vacate the dismissal of a § 2255 petition and to order evidentiary hearing regarding failure to seek suppression of un-Mirandized statements. United States v. Pressley, 990 F.3d 383 (4th Cir. 2021). On remand, first-chaired evidentiary hearing, persuaded district court to vacate client’s convictions and life sentence, negotiated favorable plea agreement, and secured client’s release.
Cruise lines in successfully defending dozens of lawsuits, including several putative class actions, arising from COVID-19 pandemic. Developed successful strategy for moving to strike jury demands, removing to federal courts, and enforcing federal statutes limiting liability in cases presenting novel issues under maritime law.
Pharmaceutical manufacturers and trade association in numerous cases related to drug pricing and disclosure laws.