The issue of whether constitutional courts should refer to foreign law has become the subject of debate and discussion around the world. In the US in particular, a heated judicial and academic debate on the issue has spilled into a political controversy extending to the introduction of federal and State Bills to prohibit judicial citation of foreign law and to Congressional proposals for such citation to be an impeachable offence. The use of foreign law, for some, is in tension with national sovereignty: one Congressman claimed that citation amounted to a surrender of lawmaking ‘to the control of foreign courts and foreign governments', and potentially represented the start of an internationalist slide in foreign policy and security and military strategy as well. However, these normative debates about foreign law play at best a muted role in Australian jurisprudential and political life, and we do not directly engage with them here. Rather, we consider to what extent, and how, Australian High Court judges engage with foreign and international legal materials in constitutional cases. In this article we track the frequency of citation in constitutional cases and provide a substantive analysis of the ways in which those materials are used.