The Legality of Nuclear Weapons
Policy Briefs

The Legality of Nuclear Weapons

Policy Brief No. 79

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Recent events have reminded us once again of the dangers of a nuclear war. The realization that “a nuclear war cannot be won and must never be fought” is stronger than ever. 

In this new APLN Policy Brief, John Carlson, former Director General of the Australian Safeguards and Non-Proliferation Office, revisits the 1996 advisory opinion of the International Court of Justice (ICJ) on the question, “Is the threat or use of nuclear weapons in any circumstances permitted under international law?”   

Following a request by United Nations General Assembly to seek an advisory opinion from the ICJ on the legality of the threat or use of nuclear weapons, the court stated that there is no source of law, customary or treaty, that explicitly prohibits the possession or even use of nuclear weapons. But it also affirmed that international humanitarian law applies and that a threat or use of force by means of nuclear weapons that is contrary to Article 2, paragraph 4, of the United Nations Charter and that fails to meet all the requirements of Article 51, is unlawful. 

John Carlson argues that international law is a means of establishing rules of conduct to mitigate existential dangers and international humanitarian law principles should be reflected in national military policies, practices and doctrines. He sets out guidelines for national positions on nuclear weapons that would reflect international legal obligations: 

  • Commitment to a policy of no first use or sole purpose – namely, the sole purpose of nuclear weapons is to deter the use of nuclear weapons by others.  As a consequence:  
    • Nuclear weapon numbers and types would be capped; there would be no “modernisation”, no new weapon systems, and no additional weapons produced. 
    • A realistic minimum credible deterrent would be determined, with the commitment to withdraw from service and eliminate nuclear weapons in excess of this deterrent. 
  • Risk reduction steps would be taken as a matter of urgency.  These include: 
    • Establishment of hotlines and other communications channels for resolving urgent questions regarding military actions possibly involving nuclear weapons. 
    • De-alerting – removing nuclear weapons from launch-on-warning readiness. 
    • Strengthening checks on launch authority.  It is simply too dangerous to have the power to initiate nuclear war in the hands of one person, or a group dominated by one person. 
  • A process of strategic dialogue would be established, involving all nuclear-armed states, to resolve major differences by diplomatic means, ensure clarification of nuclear doctrines, discuss force sizes and other specifics of nuclear deterrence, and so on.   
  • In addition, a process for arms control negotiation would be established, to reach agreement on phased reductions and related verification, transparency and confidence-building measures. 

With respect to nuclear weapons, international law expresses not only what is legally and morally right but what is essential for human survival. These rules can reduce the risk of war through establishing predictability and can help to frame moral and ethical thinking about nuclear weapons – reinforcing the “taboo” against using these weapons. 

About the Author

John Carlson is an independent consultant on nuclear safeguards, disarmament and arms control and nuclear governance. His current affiliations include: APLN; the International Luxembourg Forum; the Vienna Center for Disarmament and Non-Proliferation; and the Nuclear Threat Initiative. He was Director General of the Australian Safeguards and Non-Proliferation Office from 1989 to 2010. Concurrent appointments included chair of SAGSI, the IAEA’s Standing Advisory Group on Safeguards Implementation (2001-2006) and founding chair of the Asia-Pacific Safeguards Network (2009-12). Carlson is a Fellow of the Institute of Nuclear Materials Management, and a Member of the Order of Australia. 


Image: iStock, Murat Gocmen/ Remixed by APLN
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