The aim of this article is to analyse whether, why and with which consequences courts support or on the contrary oppose decisions taken by non-majoritarian institutions and governments, and hence constrain or, on the contrary, enhance the integration process in times of crises. Focusing on judicial decisions on the subject of the European Central Bank’s (ECB) monetary policy by the Court of Justice of the EU (CJEU) and the German Federal Constitutional Court (FCC) during the Euro area and the Covid-19 crises, the article shows that during the Euro area crisis, the European judicial system had an enhancing effect on the ECB’s monetary policy; on the contrary, it has had a constraining effect during the Covid-19 crisis.Four different institutionalist explanations are put forward, relating to: the severity of the crisis; the timing of the judgments; the legal framing of the judgments; the functioning of the judicial system.