The Court of Justice was twice invited by the German Bundesverfassungsgericht to define the limits of European Central Bank's discretion. In both judgments, the Court of Justice confirmed that the ECB acted within the limits of its mandate, and was compliant with the prohibition of monetary financing. The final decision before the German Court will offer an opportunity to test the auto-correct function of constitutional pluralism. The auto-correct function is based on a shared understanding of the division of obligations in the European judicial space, which through their behavior auto-correct any imbalance that might arise from a constitutional conflict. Two legal imperatives are driving this dynamic in two opposite directions – the principle of primacy of Union law, and the obligation to respect the national identity of Member States. The review before the two courts therefore provides an almost natural laboratory for assessing the normative strengths of constitutional pluralism.