This article sets out to explore the premise of general principles in what is labelled transnationalised criminal justice (encompassing the substantive and procedural law as well as the institutions of transnational criminal law and European criminal law). Whilst there can be no denying that these are diverse and divergent areas of law in many ways, their fundamental common denominator of seeking to convict individuals whilst subjecting these to arrest, detention and deprivation of other rights across borders, is taken as a baseline around which certain general principles may gravitate. The current state of executive over-reach within transnationalised criminal justice structures is studied, particularly in relation to the European criminal justice context. This over-reach is explored utilising the theoretical framework of social contract theory. It is suggested that the transfer of investigative and prosecutorial powers to transnationalised contexts undertaken by the relevant executives without seeking to temper this assignment with mechanisms to secure the rights of individuals which counter-balance these, as required by the constitutional traditions of their country, can be regarded as in breach of the social contract. Using this thought experiment, this article provides a framework with which to identify the deficits of transnationalised criminal law. The way in which such deficits undermine the legitimacy of the institutions created by states to operate the mechanisms of transnationalised criminal justice as well as the fundamental values of their own constitutions is, however, demonstrated as concrete. The latter are identified as mechanisms for deducing the general principles of transnationalised criminal justice (albeit via difficult international negotiation). If the supranationalisation of criminal justice powers is not to be regarded as a tool undermining constitutional values and effectively allowing executives acting in an unbalanced manner a means by which to undermine the ‘social contract’ it is argued that such general principles must be established more strongly with legal force. Ultimately the ‘social contract’ lends (at least Western democratic) governments their legitimacy. This must also urgently be protected at the supranational level.