For over a century, jurists in the Anglo-American and European continental worlds have debated whether it is justified to deprive a court of potentially crucial evidence demonstrating the guilt of the accused, when that evidence has been obtained in an unconstitutional, unlawful, or unfair manner. In fact, so controversial is the improperly obtained evidence debate that it transcends the confines of legal scholarship, entering the political sphere as part of populist discussions 'law and order', victims of crime and defendants' rights. The legal systems of England and Wales, France, Greece and the USA offer exemplary illustrations of the perennial disagreement between legal scholars, about the merits and weaknesses of an 'exclusionary doctrine' versus the doctrine of 'free proof'. In the USA the exclusionary rule is portrayed as the criminal law topic that more than any other has divided scholars and judges, liberals and conservatives, as well as the American public. In France, this area is a traditional battlefield for parties on the right and left of the political spectrum, whereas in Greece controversy causes yet more complicated dichotomies, for example between Constitutional Law and Criminal Procedure scholars or between scholars strictly adhering to German legal doctrines and those more open to Anglo-American influences. In England and Wales, the synchronisation of the 'law and order' agendas of Labour and Conservatives since the beginning of the 1990s has left the exclusionary thesis without any real support, though the judiciary more or less continued with the common law tradition of admitting improperly obtained evidence, within the confines, of a test of discretionary exclusion introduced in 1984. Yet the fallacies of the anti-exclusion approach have long been identified by legal commentators warning of the need to pay more attention to notions of judicial integrity, fairness and the protection of rights, when determining the admissibility of improperly obtained evidence. This book seeks to demonstrate that the exclusion of improperly obtained evidence is not a notion that is unique to Anglo-American law, but rather a problem that is common to Anglo-American and Continental legal systems, drawing from this the conclusion that cross-cultural exchanges in this area of law are possible and, in fact, urgently required, given the complexity, intensity and durability of the improperly obtained evidence debate, in both the Anglo-American and Continental world. The book will also facilitate critical analysis of rules of international law relating to the admissibility of improperly obtained evidence, for example those used by the International Criminal Court and international criminal tribunals, and the important case-law of the European Court of Human Rights. Examining improperly obtained evidence from a multidimensional perspective, the book addresses different types of improper means - unconstitutional, unlawful and unfair means of obtaining evidence - in relation to different types of evidence; inherently reliable tangible evidence, obtained in violation of the right to privacy and through unlawful entrapment, and inherently unreliable intangible evidence, confessional evidence in particular. At the same time, it will allow the improperly obtained evidence debate to be seen as merely bipolar, as one where a liberal and individualistic approach is in direct conflict with a conservative and collectivist one. This book will chart movements along the admissibility spectrum, before engaging with the normative questions of whether improperly obtained evidence should be excluded in order to protect rights, safeguard judicial integrity and ensure reliability of evidence admitted into criminal trials.