Yesterday's Reach: How Legal Institutions Keep Pace with Technological Change

Posted: 16 Apr 2021 Last revised: 21 May 2023

Date Written: January 2, 2020


Governments rely on armies of lawyers for all manner of tasks. Among the most important is assessing compliance with international law, which often involves the application of general purpose rules to unique constellations of facts. Yet technology often “surprises” existing law, a phenomenon legal scholars have termed the “pacing problem.” How are compliance interpretations affected by technological surprise? Dominant theory in the social sciences has long held that political discretion is minimized by textual specificity, so more specificity should increase law’s constraining effect. Instead, I argue increasing the specificity of a legal rule hampers its applicability in environments where innovations can occur. To test the theory, I commission a sample of legal experts (law school graduates and advanced law students) to write advisory briefs about hypothetical technologies, randomizing case facts along 23 randomized-controlled conditions. Contrary to null predictions, treaty law applied to novel cases at higher rates when treaty language is more abstract. Nor do political pressures influence the rate of application, suggesting that legal contestation is bounded. The theory harmonizes two parallel but largely compartmentalized literatures in the study of international law and international security — evasive compliance and technological determinism — by explaining how they interact. International law may evolve according to what states say it is, but there are limits to what their lawyers can justify.

Keywords: international law, law, arms control, compliance, technology, survey experiments, disarmament, foreign policy, hypernymy, political psychology

Suggested Citation

Canfil, Justin Key, Yesterday's Reach: How Legal Institutions Keep Pace with Technological Change (January 2, 2020). Available at SSRN:

Justin Key Canfil (Contact Author)

Harvard Kennedy School

79 JFK Street
Cambridge, MA 02138
United States

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