Considering the current ecological crisis, the concept of sustainable development, or ‘sustainability’ appears to have failed to meet the goals laid out by its authors at the 1992 Earth Summit of Rio de Janeiro. Sustainable development was originally perceived as the torchbearer of a new project, a new hope of protecting humanity’s general interest, a ‘magic formula meant to reconcile free trade, economic growth and environment’. As it turns out, the contradiction inherent in sustainable development has never been wholly resolved: ‘In Rio, some countries talked about the environment only, whereas others talked about development only’. Today, a sense of scepticism, of wariness towards a ‘superficial ecology,’ reflects the failure of sustainable development to fulfill its original mission of preserving the environment, having ultimately become a simple foil for ‘soft’ economic growth, also known as ‘green growth’. In other words, development has prevailed over sustainability. Multiple technologies and ‘low-tech innovations’ have been developed to curb the adverse effects of economic growth, but they never genuinely challenge the imperative of growth. This raises the question of what kind of economy and by extension what kind of future we want, at odds with the fatalistic view that we are ‘destined to produce not only goods, but also new servitudes’. Sobriety – from the Latin sobrietas – in the sense of caution, moderation, temperance or frugality, as opposed to ‘sustainability’ understood as green growth as the only possible horizon, should help us conceive a different approach to environmental protection. This involves no longer only limiting the consumption of natural resources, but seriously considering not using them all. Generally, sobriety should be conceived functionally, meaning that it is liable to change behaviours. Drawing on such an approach, the introduction of an ‘environmental ceiling’ and a ‘social foundation’ has been suggested to work towards a ‘resilient’ development, tackling a wide range of issues, including environmental inequalities. Is the idea of sobriety a new concept that may allow us to resolve the contradictions inherent in the sustainable development concept? Can it help change behaviours in law?