With the principle of mutual recognition, the EU facilitates effective and efficient law enforcement cooperation among its Member States. Foreign judicial decisions are treated like domestic decisions, while differences in the national criminal justice systems are maintained. Prolonged examinations are no longer necessary and “safe havens” for criminals are closed. The basis of this cooperation, however, is mutual trust in the rule of law. The author uses, inter alia, the current example of Encrochat to show concrete possibilities for application. There, the French criminal authorities achieved a considerable cross-border investigative success by decrypting crypto-mobile devices of that company, which were frequently used by criminals. Through the recognition and execution of European Investigation Orders in France, those findings could also be used in other Member States and considerable prosecution successes achieved. However, the scope and variety of such measures can lead to problems: Only corresponding measures can be recognised. Violations of the Charter of Fundamental Rights EU must not be enforced. Inhumane treatment of detainees may prevent the enforcement of a European Arrest Warrant in individual cases. The loss of trust in the rule of law in some Member States, the EUs reaction to this danger and the control function of CJEU decisions are currently determining legal policy.