William Powell
Senior Counsel
William Powell is Senior Counsel at the Institute for Constitutional Advocacy and Protection. In his role at ICAP, Bill litigates cases at all levels of the state and federal courts to vindicate civil rights, promote the rule of law, and defend the Constitution.
Bill’s generalist practice runs the gamut of ICAP’s issue areas. He leads CASA v. Trump, ICAP’s challenge to President Trump’s Executive Orders purporting to limit birthright citizenship, in which ICAP secured the first preliminary injunctions in the nation against both the President’s initial birthright Executive Order in 2025 and his second Executive Order in 2026. Bill has extensive experience litigating First Amendment issues, including in Brown v. Yost, a challenge to Ohio’s restrictions on ballot initiatives; Barred Business v. Kemp, a challenge to a George law limiting charitable bail funds; and Jolt v. Paxton, defending a voting-rights nonprofit against a retaliatory campaign by the Texas Attorney General to revoke its corporate charter.
Bill also has extensive appellate experience, including in the Supreme Court. He was counsel of record in the Supreme Court for Davis v. Ermold, in which ICAP successfully persuaded the Court not to reconsider its landmark decision in Obergefell v. Hodges that recognized the constitutional right of same-sex couples to marry. He has briefed several Supreme Court merits cases, including Grants Pass v. Johnson, on behalf of a class of involuntarily homeless residents challenging a local ordinance criminalizing homelessness; NRA v. Vullo, on behalf of a New York state official who sought to enforce the law against the NRA’s concededly unlawful conduct; and Wolford v. Lopez, on behalf of the State of Hawaii defending is law requiring consent before carrying a gun onto someone else’s private property. He has also argued several appeals, including Welty v. Dunaway, a First Amendment challenge to Tennessee’s restriction on abortion “recruiting”; Fonseca v. Barringer, a First Amendment challenge to a journalist’s arrest while reporting on the clearance of a homeless encampment in a public park; and In re Office of the Attorney General, defending a nun who runs an immigration shelter against a retaliatory investigation by the Texas Attorney General.
Before joining ICAP, he served as a Bristow Fellow in the Office of the Solicitor General at the Department of Justice, where he helped litigate cases in the Supreme Court on behalf of the federal government. Bill previously served as a law clerk to Chief Judge Sri Srinivasan of the U.S. Court of Appeals for the District of Columbia Circuit and to Judge Randolph D. Moss of the U.S. District Court for the District of Columbia. Before his clerkships, Bill served as a legal fellow at the Reporters Committee for Freedom of the Press, where he provided pro bono legal services to journalists and litigated press-freedom cases in state and federal courts.
Bill received his law degree from Yale Law School, where he was a notes editor on the Yale Law Journal, a Coker Fellow, and a member of the capital punishment clinic. Before law school, he worked for several years as a journalist. He wrote magazine stories about the Ferguson protests, the death penalty, and homelessness, among many other topics. He received his undergraduate degree from the University of Missouri.
