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'Defend Forward' and Sovereignty

Jack Goldsmith, Alex Loomis
Friday, April 30, 2021, 11:26 AM

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Among the most discussed provisions of the Tallinn Manual 2.0 is Rule 4: “Violation of sovereignty.” Rule 4 provides: “A State must not conduct cyber operations that violate the sovereignty of another State.” Considered alone, Rule 4 is banal and unobjectionable, since there are many established sovereignty-based international-law rules that cyber operations might violate. For example, the UN Charter’s prohibition on certain uses of force and the customary international-law rule of nonintervention constrains cyber operations by one state in another. The hard question is whether international law related to sovereignty prohibits anything more. Here the commentary to Rule 4 is quite ambitious. It argues that a stand-alone customary international-law concept of state sovereignty operates to regulate and render illegal certain cyber operations that would not otherwise be illegal under any of the specific and acknowledged sovereignty-based rules of international law. This paper argues that the discrete rules articulated in the Rule 4 commentary do not reflect customary international law. The Rule 4 commentary cites very little legal authority in support of its bold conclusions and lacks any practical connection to the complex interplay of extensive state practice and opinio juris that constitutes customary international law.

Jack Goldsmith is the Learned Hand Professor at Harvard Law School, co-founder of Lawfare, and a Non-Resident Senior Fellow at the American Enterprise Institute. Before coming to Harvard, Professor Goldsmith served as Assistant Attorney General, Office of Legal Counsel from 2003-2004, and Special Counsel to the Department of Defense from 2002-2003.
Alex Loomis graduated magna cum laude from Harvard Law School. While in law school, he interned in the International Affairs Division of the Office of General Counsel of the Defense Department, as well as the Office of the Legal Adviser at the State Department. He graduated cum laude from Harvard college in 2012.

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