Nuclear weapons destroyed Hiroshima and Nagasaki in World War II, and more than 10,000 of them still exist today. Even after the Cold War, risks like accidental launch or terrorism remain. Founded in 2007, ICAN united NGOs of doctors, lawyers, and students, placing the “humanitarian impact” of nuclear weapons at the center of debate. They brought testimonies of survivors and medical experts to UN meetings, stressing the protection of human life rather than pure national security. As a result, in July 2017 the Treaty on the Prohibition of Nuclear Weapons was adopted with the support of 122 countries. The treaty completely bans development, testing, possession, and threats of use, and requires states to assist victims and clean contaminated areas. Although nuclear-armed states have not joined, the treaty questions the morality of nuclear deterrence and influences global public opinion. Recognizing this grass-roots movement, the Nobel Committee awarded ICAN the Peace Prize.

The Treaty on the Prohibition of Nuclear Weapons (TPNW) is the first multilateral instrument that legally bans nuclear weapons in their entirety, and its negotiation was driven by ICAN’s lobbying from its headquarters in Geneva. ICAN collaborated with the International Red Cross and Red Crescent Movement and IPPNW, translating scientific evidence about acute radiation sickness, long-term cancer risks, and climate models predicting a “nuclear winter” into policy language. This so-called “humanitarian initiative” united non-nuclear-weapon states frustrated with the stalled NPT Review Process, leading to ministerial conferences in Oslo, Nayarit, and Vienna. The text adopted in 2017 prohibits development, testing, manufacture, possession, deployment, threat, and use of nuclear weapons, and obliges state parties to assist victims and restore contaminated environments. Article 4 anticipates future accession by nuclear-armed states, outlining a roadmap for verified dismantlement in cooperation with the IAEA. However, the United States, Russia, China, and NATO allies boycotted the negotiation, so the treaty’s effectiveness depends heavily on international politics and security dynamics. After entry into force, ICAN has promoted initiatives such as the ‘Cities Appeal’ and transparency reports on financial institutions’ investments in nuclear-weapon producers to propagate the norm. This civil-society-led norm entrepreneurship is an important case for constructivist International Relations theory and studies on the creation of international law. Storytelling based on survivors’ testimonies and social media mobilization intersects with media studies and memory studies, making the campaign highly interdisciplinary. The Nobel Peace Prize thus formally recognized the role of non-state actors and became a symbolic boost to future nuclear-disarmament mechanisms.

ICAN’s strategy represents a “norm-entrepreneurial” approach that bypasses the NPT-based nuclear order by invoking International Humanitarian Law (IHL) to delegitimize nuclear weapons. The network fused an epistemic community with an advocacy network, front-loading testimony by physicians, jurists, diplomats, and survivors. During the 2013-14 humanitarian impact conferences it translated peer-reviewed data and climate models (e.g., Robock 2007) into policy language, reframing disarmament from the security regime to the IHL regime. Like-minded states such as Austria, Mexico, and New Zealand chaired negotiations, borrowing precedents from the ICBL/MBT to insert provisions on environmental remediation and victim assistance. Article 4 hints at verification by a competent international authority while deferring detailed protocols, thus preserving late-accession options for nuclear-armed states. Deterrence powers dismiss the treaty as “unrealistic,” yet mobilization of financial divestment is exposing supply-chain and brand risks. Since its entry into force in January 2021, the UN depository function and CSP1 architecture have offered a new case of IHL-arms-control hybridity. ICAN’s “Don’t Bank on the Bomb” database provides ESG benchmarks for CSR investment researchers. Future challenges include legal compatibility with NATO nuclear-sharing, cost-benefit analysis of latent nuclear states’ disarmament, and mechanisms for Article 12 norm diffusion obligations. Overall, ICAN exemplifies the interaction of transnational advocacy, legal norm building, and financial discipline, energizing meta-theoretical debates in IR, international law, and peace studies.