The Institute of International Law was founded on September 8, 1873 in Ghent, Belgium. Since then, the association of lawyers has been committed to the development of international law and thus of public international law and private international law.

Political decisions are analyzed and advised through academic research and constructive proposals. The organization was awarded the Nobel Peace Prize in 1904 for this commitment. The statutory maximum number of 132 legal experts meets regularly to discuss current developments.

At a congress in Wiesbaden on August 12, 1975, leading representatives of the Institute were received by the magistrate in the ballroom of the town hall. Lord Mayor Rudi Schmitt praised the work of the learned society and thanked the city for choosing Wiesbaden as the venue for the congress. Chairman Wilhelm Wengler then explained that he was only too happy to have organized the meeting in his home town. He and the Presidium then signed the city's Golden Book.