This special issue is focusing on the dramatic weakening of liberal constitutionalism and the rule of law, apparent in Hungary and Poland during the last few years. It is actually focusing on the constitutional crisis brought about by the Hungarian PM Viktor Orbán and his Hungarian Civic Alliance (Fidesz) party since 2010 and the Polish Law and Justice (Prawo i Sprawiedliwość, PiS) party and its leader Jarosław Kaczyński since 2015. The Hungarian and Polish problem has received much publicity and has frequently been discussed by the various organs of the European Union (triggering Article 7 on sanctions against Poland for the violation of the rule of law). It has acquired an ever-growing interest of the academic community. The issue sheds light to new perspectives of European development in the Eastern members of the EU by providing a cross-disciplinary investigation on the concept of the rule of law. Our approaches combine legal theory, constitutional law, European and international law, political philosophy, political science, international relations and political history.