The article provides an analysis of interaction of the principle of sustainability and environmental protection in the case law of the Constitutional Court. The principle of sustainability in Latvian constitutional law is a quite new one. Still, it is applied by the Constitutional Court reviewing different cases. It is included also in the written text of the Constitution and all development of the state is focused on sustainability. As environmental protection is the core of this principle, the Constitutional Court has applied it by solving different environmental issues. The article points out also the content of environmental constitutionalism. Namely, in Latvia, it is implemented also as a specific fundamental right to live in a benevolent environment. Legal remedies such as those before the administrative court and the Constitutional Court are analysed which can be used to protect violated fundamental rights. To get insight into the case law of the Constitutional Court, three different issues are explained. First, the importance of agricultural land and its cultivation and protection by achieving the idea of sustainability is given. Then the author explains the main arguments of the application of this principle in spatial planning. In the end, sustainable energy cases where sustainability is applied lead to conclusions about the future and importance of renewable sources.