Glennon has written on public international law, the international use of force, foreign relations and national security law, constitutional law, free speech, international human rights, nuclear non-proliferation, and international environmental law. He published
Constitutional Diplomacy in 1990, arguing against executive supremacy in U.S. foreign policy, and advocating a stronger role for Congress and the judiciary in shaping diplomatic and national security decisions. In a review for
The New York Times,
Herbert Mitgang stated, "...it is hard to imagine a book that is more prescient and provocative about the huge military buildup in the Persian Gulf... Glennon writes as if he had a crystal ball that foretold the events." He further analyzed flaws in the U.S. presidential selection process and proposed reforms in
When No Majority Rules: The Electoral College and Presidential Succession (1992). His 2001 work,
Limits of Law, Prerogatives of Power: Interventionism after Kosovo, examined the erosion of international legal constraints on military intervention and its implications for U.S. policy, and was described as the "best book written on international law and the use of force in the past forty years..." by
Anthony Clark Arend. In 2010, Glennon challenged traditional theories of legal obligation by contending that international law is binding only when enough states choose to honor it in
The Fog of Law: Pragmatism, Security, and International Law, which was regarded as a "landmark book" by G. John Ikenberry in
Foreign Affairs. He authored
National Security and Double Government in 2016, arguing that U.S. security policy is controlled by an unelected "Trumanite network" of military, intelligence, and law enforcement officials, while traditional democratic institutions play only an illusory role.
Christopher Coyne remarked, "Glennon's analysis shows how the national security apparatus is a threat to the very freedoms its inhabitants and supporters purport to protect." The same year, he co-authored (with Robert Sloane)
Foreign Affairs Federalism: The Myth of National Exclusivity, which the
Harvard Law Review described as "an informative and valuable contribution to the literature on federalism and foreign affairs." Glennon's latest work,
Free Speech and Turbulent Freedom: The Dangerous Allure of Censorship in the Digital Era (2024) critiqued the fusion of public and private power in online censorship, arguing that protecting even harmful speech is essential to preserving democracy's marketplace of ideas. Glennon’s shorter writings have appeared in
The New York Times,
The Washington Post,
Time Magazine,
Financial Times,
Frankfurter Allgemeine Zeitung,
Foreign Affairs, and
Harper’s Magazine. ==Bibliography==