The history of transnational governance stretches back as far as ancient and mediaeval times. Communities of states were regulated by law in ancient Greece, and recently by the modern law of nations' that developed in Europe in the sixteenth and seventeenth centuries. Transnational systems of governance developed in different ways during the nineteenth century. Compared to the burgeoning literature that discusses internationalisation and globalisation in the twentieth century, scholars have neglected the systems of transnational governance that emerged in the nineteenth century. This chapter shows how the English common law was itself an important form of transnational governance in the nineteenth century, by causing similar legal principles to be applied across national borders. The American colonies inherited the basic structure of the English criminal law. The similarities in the reform of the criminal law and the enforcement of that law in the Anglo-American world meant that the criminal law formed part of an emerging transnational system of governance.