In 1918 Santi Romano published his Corso di diritto coloniale and the text immediately stood out for its originality. Romano presented the matter in new terms. Colonial law was a knowledge in search of theoretical legitimacy and scientific autonomy. It was necessary to define its nature, draw the boundaries that separated it from national law and international law, give form to the system of differences on which it was based, and finally reflect on the changes that colonial expansionism had produced in the structures of the old liberal State. But why did a star of public law as Romano feel the need to deal with colonial law? What were the connections between this handbook on colonial law and his masterpiece on The Legal Order ? Which is the place of the handbook in his intellectual path? The article aims to answer these questions, reconstructing the influences of the German doctrine on Romano, the role played by the State within a pluralistic legal order and the use of time as an instrument of coexistence between the metropolitan legal order and the colonial one.