This contribution argues that recent Europe-decisions of national constitutional courts demonstrate a new quality of comparative legal reasoning. Whereas classic EU related case-law reflects comparative law dimensions at best by sporadic references to foreign case law, some constitutional courts in Europe have now taken a path towards a more elaborate use of comparative reasoning, including in-depth and sometimes even critical evaluations of foreign jurisprudence in the ratio decidendi. Beyond the traditional motives for courts to rely on comparative law, one particular reason for this intensification seems to be the aim to take an active role in an EU-wide process of shaping a common constitutional law. Seen in a transnational perspective, comparative reasoning by judges can be more than a mere reference to foreign law as such: In fact, the judicial evaluation of foreign Europe-decisions can simultaneously be an evaluation of propositions on common constitutional standards. Comparative reasoning by courts then becomes an active contribution to a transnational dialogue of judges on the making of a common constitutional law in Europe.