Summary This paper is a study of the preliminary ruling procedure in EU law, and focuses on the case of the German Federal Constitutional Court in March 2021. The case concerned the right to a fair trial by a legal judge as stipulated in the 2nd sentence of article 101（1) of the Basic Law for the Federal Republic of Germany . In other words, the issue was that the German Federal Fiscal Court did not ask the Court of Justice of the European Union for a preliminary ruling under the German Constitution.