'Sustainability’ – the idea that those living have a responsibility to leave for future generations an environment at least as livable as presently enjoyed – has witnessed dispersive distribution, including applications to energy policy, constitutionalism, and the concept of ‘sustainable development’. The latter has become a common if not ubiquitous feature in legal expressions at the international, national and subnational levels, culminating in the United Nations setting 17 Sustainable Development Goals (SDGs) to achieve by 2030