For a long period of time, EU criminal law fell outside of the scope of EU legislative competences. Criminal law stood at the core of national sovereignty, and would express (solely) national-cultural values of a State. With the coming into force of the Treaty of Lisbon, criminal law became one of the components of the Union’s objectives. However, EU criminal law has always remained a sensitive policy area. For that reason, mutual recognition instruments, such as the EAW, were often seen as an alternative for EU criminalisation. Nevertheless, under the current legal framework EU criminalisation competences are inextricably bound to judicial cooperation in criminal matters (Cf. Title V – Judicial cooperation in criminal matters, Treaty on the Functioning of the European Union). It has been recognised that common minimum rules on substantive criminal law facilitate the principle of mutual recognition, and thus, enable judicial cooperation on the basis of mutual recognition instruments (Cf. Council document 8619/19). This raises the question of whether the applicability of mutual recognition instruments such as the EAW should be considered when criminalising certain acts under EU law. The use of EU criminal law requires careful consideration and coherent application. Criminalisation principles help to legitimise, justify and facilitate the criminalisation process and create more coherence. They can be used to determine whether and how conduct should be criminalised at EU level. Criminalisation principles that can be considered are inter alia harm, Rechtsgut, attribution of powers (legal basis), proportionality and effectiveness. When criminalising certain conduct, it should be noted that judicial cooperation instruments can have serious consequences for suspects, such as violations of the right to privacy, deprivation of liberty awaiting the execution of an EAW, and the transfer to and awaiting trial in the issuing Member State. In addition, lack of capacity within the judicial system could constrain the good functioning of mutual recognition instruments. Therefore, it should be determined whether the applicability of mutual recognition instruments such as the EAW should be applied as a separate criminalisation principle (e.g. the principle of mutual recognition as criminalisation principle), or whether it serves as an argument for or against criminalisation under one of the identified criminalisation principles (e.g. proportionality, effectiveness). In this presentation I aim to determine whether and, if so, how the applicability of the EAW should be assessed in light of EU criminalisation competences. It examines the interaction between criminalisation and judicial cooperation at EU level. That way it will contribute to a better understanding of harmonisation measures in light of the principle of mutual recognition.