Like other decision-making processes in which human beings are involved, judicial decision-making is subjected to certain biases that run counter the rationality assumption. A particularly visible and far-reaching example of this phenomenon can be found in the jurisprudence of domestic constitutional courts, particularly in the context of their interaction with the CJEU and with constitutional courts of other states. With reference to the categories of biases established in behavioural science, this paper will highlight how the constitutional courts‘ use of “constitutional identity“ as an argumentative tool can be seen as an expression of different biases that relate to the self-understanding of the court and its role in the domestic constitutional setting as well as to their perceived position in the dialogue with other external courts.