Modern constitutionalism has put a lot of hopes in parliaments but there is some consensus that these hopes have not been entirely fulfilled. At the same time, the role of parliaments in contemporary democracies continues to evolve as parliaments are faced with new challenges. How should they react to the new forms of executive and administrative action? Should they play a role in upholding judicial independence, although the latter is frequently seen as independence from parliament as well as the executive? How should they contribute to the protection of fundamental rights? The book aims at providing some answers to these questions by first setting the historic scene, giving a comparative overview of the modern history of a selection of major European deliberative institutions (UK, France, Germany and the European Parliament). The book then looks at themes around the doctrine of separation of powers, especially aspects of the relationship between parliament and the executive power and parliaments' role and attitude regarding the judiciary with a special focus on the independence of the judiciary in a comparative perspective.