Of Carbon Budgets, Factual Uncertainties and Intergenerational Equity – The German Constitutional Court’s Climate Decision

The German Federal Constitutional Court’s climate decision provides a nuanced acknowledgment of climate change’s constitutional relevance. In this article, the author critically assesses how the Court innovatively sought to capture the intergenerational equity dimension of climate mitigation through a combination of negative and positive duties stemming from constitutional law. The article demonstrates how despite progressive findings on intergenerational equity and the innovative invocation of negative duties, the operative part of the decision turned out to be rather limited. Because of remaining uncertainties about the allowable national carbon budget the Court was unable to require the legislator to enact a stricter reduction path. The author argues that the Court could have narrowed remaining uncertainties, without engaging in judicial activism, by adopting an international and constitutional minimum approach to calculating the national budget and by adjusting the burden of proof. Finally, the article highlights how the German legislator by going beyond what was required by the Court ‘trapped’ itself on an ambitious reduction path, opening opportunities for future constitutional complaints.