After the Supreme Court of Canada’s decision in Nevsun Resources Ltd. v. Araya, Canadian courts can, in theory, apply customary international law (CIL) to private corporate actors for the purposes of a transnational tort claim pursuant to allegations related to human rights and/or environmental harms. The Court found a tort claim grounded in CIL to be symbolically different than existing causes of action as it is of a public nature that tends to shock the conscience of humanity. To respect CIL’s distinct status, I argue Canadian courts should assert jurisdiction over a related tort claim in limited circumstances when a corporate defendant has behaved abroad like a state actor by discharging what were traditionally regarded as public functions vis-a-vis host state populations. Pursuant to what I term a ‘functional approach’, a corporate CIL tort would only be available in two discrete instances. In the first, a court would assess whether the corporation has become what Butler calls a ‘semi-state’ by displacing a failed or fragile host state government in the provision of, for instance, food, shelter, infrastructure, healthcare, and public security. In the second, a CIL tort would be available when an investor-state arrangement specifically concerns the provision of public goods and/or services to a host state population such as utilities, infrastructure, transportation, or immigration control. Applying a functional approach in this manner would avoid a dissonance post-Nevsun between CIL’s heightened status and the availability of a related tort on every occasion a corporate actor invests and subsequently commits harm abroad. It would also more closely align with U.S. jurisprudence as well as CIL’s historical understanding by international organizations and tribunals.