The Institute was created in 1958 by the merger of the Society of Comparative Legislation (founded in 1895) and the Grotius Society (founded in 1915 and named after the 16th century Dutch jurist regarded as one of the founders of international law). This merger created an independent research body, unaffiliated to any university, which is committed to the understanding, development and practical application of international and comparative law. It is both a limited company under UK law, and a registered charity.
The Institute continues its mission first begun in 1895:
- To advance the understanding of international and comparative law;
- To promote the rule of law in international affairs; and
- To promote their application through research, publications and events.
A brief history of the Institute was prepared by Norman S Marsh QC, the Institute's first Director, to celebrate its 40th Anniversary on 17 November 1998. It sets out the history of the Institute prior to its formal incorporation in 1958.