The CMI, which was formally established in 1897, is the oldest international organization in the maritime field. Although its foundation followed that of the International Law Association (ILA) by several years, and the CMI was perhaps in one sense a descendant of the ILA, the Comité was the first international organization concerned exclusively with maritime law and related commercial practices.

The known historical record makes it difficult to say with certainty when the CMI began its existence. Its origins lie in the efforts of a group led by Belgian commercial and political persons who came together in the early 1880's to discuss and to put before the ILA a proposal to codify the whole body of maritime international law. As extreme as this sounds in the present day, the roots of the effort run back to the 17th century when there were attempts to make a ‘universal’ codification of uniform principles extracted from the various mediaeval maritime codes. This theme had been picked up by maritime jurists in the first half of the 19th century, when it was commonly acknowledged that the courts of admiralty and maritime law were courts of international law. In the common law system this view gathered strength from landmark judgements in England and America that were founded upon declared universal principles. The latter half of the 19th century was an age of idealism in international law, and the quest for uniformity in maritime law was given greater impetus when the first collision regulations began to be adopted on a wide geographical scale by national legislation in the 1860s. At about the same time the first international codification of principles of general average was drawn up in London, and this culminated in the ILA Conference of 1890 that adopted the first York/Antwerp Rules. It should also be borne in mind that until the mid-20th century there were academic maritime lawyers in several countries who could make an arguable claim to know the whole body of their national maritime law as well as the common principles of international maritime law. While the effort over a century ago to make an international codification of maritime law would have been gargantuan, the ideals of that time made the obstacles appear smaller than reality.

The discussions of the early 1880s included plans for a diplomatic conference to effect the proposed codification, and such a conference was organised and hosted by the Belgian Government and held in Antwerp in 1885. When the 1885 Conference failed to accomplish the task, a second diplomatic conference was held in Brussels in 1888. While one may regret that the 1888 Conference also failed to attain what was in retrospect an over-ambitious goal, it is clear that the CMI was formally organised as a direct outgrowth of the two failed diplomatic conferences. In the aftermath of the 1888 Conference the ILA lost its appetite for continued work on unification of maritime law, and it was eventually agreed between the ILA and the interests who wished to carry on the work that a specialist organization should be formed to pursue this goal.

The agreement with the ILA was announced in a circular letter from the Comité Maritime International dated 2 July 1896; thus we know that the CMI was already in existence and functioning at least in a limited way for some period prior to its formal establishment in 1897. The letter stated the decision that the CMI would promote the establishment of national associations of maritime law, and would ensure a structured relationship between these associations. It was also stated that the national associations should be comprised of jurists, mercantile and insurance interests, shipowners, and all others concerned with maritime commerce. Finally, the Comité's letter stated that the first task to be undertaken in the pursuit of unification would be the international codification of the law relating to collision at sea.