Customary International Law Workshop

Date & time
1.15–5.30pm Thursday 16 March 2017

Finkel Theatre

John Curtin School of Medical Research, Building 131, Garran Road, The Australian National University


For interstate visitors, we offer suggestions for accommodation near ANU.

Nicole Harman

Presented by The Centre for International & Public Law

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This workshop explores how we see customary international law and its evolution in today’s uncertain times. States never put into doubt the existence of custom as a source of law, but debate does exist on what characterises custom and the extent to which it is shaped by law. Our understanding of the nature of custom in turn shapes our appreciation of what is, in material terms, current international law – the parameters of the prohibition on the use of force being an obvious example.

The workshop first addresses two contemporary frameworks for a consideration of custom – those provided by the International Law’s Commission’s recent work –, and then focuses on custom’s traditional elements; practice and opinio juris sive necessitatis. What is relevant practice for the purposes of the law? To what extent might it include for instance secretive practice? Need practice encompass an element of intention and if so how does this differ from opinio juris? Indeed, is opinio juris still relevant today? How might custom’s subjective element be affected depending on the nature of the asserted practice (obligation, prohibition, or permission)? And crucially, in today’s fast paced digital world, how do temporal factors impact custom’s subjective element, which is also to ask, what can we say now of the idea of instant custom? 


  • Professor Chester Brown »

    University of Sydney Law School

  • Henry Burmester, AO, QC »

    Honorary Professor, ANU College of Law, Australian National University

  • Hilary Charlesworth »

    Distinguished Professor, Australian National University and Melbourne Laureate Professor, Melbourne Law School

  • Dr Sarah Heathcote »

    Associate Professor, ANU College of Law, Australian National University

  • Dr Etienne Henry »

    Visiting Fellow, ANU College of Law, Australian National University

  • Jane McCosker »

    Office of International Law, Attorney-General’s Department 

  • Dr Rob McLaughlin »

    Associate Professor, ANU College of Law, Australian National University

  • Dr Anthea Roberts »

    Associate Professor, Centre for International Governance and Justice, RegNet, Australian National University
  • Julian Wyatt »

    Associate, Lalive, Geneva

Additional Materials

Research theme: 

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