Over the past twenty years, the separation of powers has undergone notable recalibration, with Congress’ authority wax and wane while presidential power expanded in key areas. According to the editors of a long-running constitutional law casebook, the new edition captures this evolution and highlights where the court may be headed next.
The realignment of the separation of powers
Late-breaking changes for the legislative power
The casebook’s coverage of Congress’ powers remained largely stable after its first edition in 2008. Earlier that decade, the Rehnquist Court’s federalism turn appeared to restrain federal authority. United States v. Lopez and United States v. Morrison set limits on using the commerce clause to reach guns in school zones and domestic violence. That trajectory slowed with Gonzales v. Raich, which upheld federal regulation of locally grown marijuana.
The second edition added NFIB v. Sebelius. The court concluded the Affordable Care Act’s individual mandate exceeded Congress’ commerce and necessary and proper powers, though the penalty survived as a tax.
For years afterward, the justices showed little appetite for revisiting the scope of enumerated powers. The newest edition departs from that pattern. Landor v. Louisiana Department of Public Safety and Corrections addresses the intersection of the spending power and the necessary and proper clause. The court concluded that the Religious Land Use and Institutionalized Persons Act does not authorize suits for money damages against nonconsenting state officials, describing such a remedy as not a proper exercise of federal power. The book also includes Justice Clarence Thomas’s concurrence in United States v. Hemani, urging a tighter link between interstate commerce and the conduct being regulated in so-called “jurisdictional hook” cases.
The editors see fresh momentum for reexamining enumerated powers.
The contracting and expanding executive power
When the first edition appeared in March 2008, the court was focused on the legal framework of the global war on terror. Hamdi v. Rumsfeld and Hamdan v. Rumsfeld featured prominently, and Boumediene v. Bush soon followed, extending the writ of habeas corpus to detainees at Guantanamo Bay. That line of cases proved short-lived as the conflict’s salience receded for the court and for a generation of students with no direct memory of Sept. 11, 2001.
The realignment of the separation of powers
The separation-of-powers chapter saw the most change across five editions, reflecting shifting perceptions of what counts as separation-of-powers versus executive power. Three cases endured throughout: United States v. Nixon, which required compliance with a subpoena for the Watergate tapes. Morrison v. Olson, which sustained the independent counsel statute. And Clinton v. Jones, which allowed a civil suit against a sitting president for pre-office conduct.
The editors debated retaining Morrison in light of Trump v. Slaughter, a 2026 decision that overruled Humphrey’s Executor v. United States and permitted the president to remove members of certain independent agencies.
Several Burger Court landmarks were dropped from later editions. Dames & Moore v. Regan upheld the suspension of claims tied to the Iran hostage crisis. Nixon v. Fitzgerald recognized immunity for certain presidential acts. INS v. Chadha struck down the one-house legislative veto. Although once central, their practical importance diminished. Still, as Justice Neil Gorsuch observed in a concurrence in Learning Resources v. Trump, the 2026 tariffs dispute, Chadha’s impact has grown as the court has allowed broader presidential control over agencies even where Congress initially paired delegations with legislative vetoes.
Early Roberts Court decisions also rotated out. Trump v. Slaughter supplanted Free Enterprise Fund v. PCAOB and Seila Law v. CFPB, both of which curtailed limits on presidential removal but now carry less weight. NLRB v. Noel Canning, which interpreted the recess appointments clause, has faded as recent presidents have relied on alternative methods for temporary appointments.
President Donald Trump’s tenure marked a pivotal period for separation-of-powers jurisprudence. Five cases bearing his name now anchor the chapter. Trump v. Vance addressed access to the president’s tax returns. The latest edition adds four more: Trump v. United States, which broadened presidential immunity beyond the Nixon era. Trump v. Slaughter, which, as noted, toppled Humphrey’s Executor while leaving Morrison in a twilight zone. Trump v. Cook, which reaffirmed the Federal Reserve’s independence. And Learning Resources, Inc. v. Trump, which invalidated tariffs imposed by the president. The editors predict that Slaughter, in particular, will spur a new wave of litigation testing the boundaries of the separation of powers.
Conclusion
Until the fourth edition in 2022, constitutional law followed a familiar arc: the New Deal framework remained secure, federalism limits were modest, the administrative state was largely unassailable, classifications targeting disfavored groups drew heightened scrutiny, race-conscious measures deemed benign could pass muster, and a strict church-state divide prevailed. The past five years have unsettled each element of that narrative. The Roberts Court has continued to pare back precedents from the 1970s and 1980s, even as many from the 1960s and earlier endure.
The editors note that professors and students, trained in an era of relative stability, have struggled to adjust to rapid doctrinal shifts. Their stated aim, as casebook editors and teachers, is to guide readers through the full sweep of constitutional law from the founding to the present, without nostalgia or bias.