Treaty Law to Signal to Outsiders: The Case of the Treaty on the Prohibition of Nuclear Weapons

Treaty Law to Signal to Outsiders

Treaty Law to Signal to Outsiders: The Case of the Treaty on the Prohibition of Nuclear Weapons

By Tobias Vestner, Head of Research and Policy Advice & Head of Security and Law at the GCSP

The Treaty on the Prohibition of Nuclear Weapons (TPNW) comprehensively and unequivocally prohibits nuclear weapons. The treaty was created to foster and diffuse norms against nuclear weapons, thereby stigmatizing and delegitimizing nuclear weapons and deterrence. The TPNW’s nature as formal treaty under international law suggests, however, that the TPNW primarily serves signaling to states which have not adhered to the treaty, in particular nuclear weapon states. This article develops how treaty law enables signaling to outsiders. Treaty law notably offers visibility, screens between “insiders” and “outsiders,” communicates substance, and provides credibility to the signal. In line with treaty law’s finality to establish and maintain international cooperation, this tempers political confrontation and, by sending information and reducing uncertainty, creates a basis for extra-regime cooperation. The article then demonstrates how and what the TPNW signals, namely that nuclear weapons are illegal, immoral, and dangerous and that nuclear disarmament should advance. The article contends that the TPNW most effectively signals that its States parties want nothing to do with nuclear weapons. Thereby, the TPNW resembles treaties establishing nuclear weapons free zones (NWFZ) and provides a basis for negative security assurances (NSA), which would represent a form of contracting between TPNW States parties and nuclear weapon states. The article concludes that assessments of political effects of international treaties need to consider their formality and legal consequences to a greater extent.

Disclaimer: The views, information and opinions expressed in the written publications (originally published in Washington International Law Journal) are the authors’ own and do not necessarily reflect those shared by the Geneva Centre for Security Policy or its employees. The GCSP is not responsible for and may not always verify the accuracy of the information contained in the written publications submitted by a writer.

Tobias Vestner leads GCSP’s Research and Policy Advice Department as well as the Security and Law Programme. He oversees and manages GCSP’s analysis and advice activities as well as researches and teaches on the intersection between security policy and international law. Tobias Vestner regularly advises governments, international organizations, and private firms on global security and legal issues. He has published several books and papers (see below) and provided insights to various media outlets, including the U.S. National Public Radio, NBC News, Neue Zürcher Zeitung, and RTS Geopolitis.