On March 20, 2018, the Grand Chamber of the Court of Justice of the European Union ruled that that the ne bis in idem principle, an individual’s right not be prosecuted or punished twice for the same offense, may be restricted in order to protect EU financial interests and markets. According to the press release, in Menci, a case concerning an individual’s failure to pay VAT for a year, and Garlsson Real Estate and Others, a case concerning market manipulation, the Court held that in situations like these with potential administrative and criminal penalties “there could be a duplication of ‘criminal proceedings/penalties’ and ‘administrative proceedings/penalties of a criminal nature’ against the same person with respect to the same acts.” The Court found that such a limitation must “pursue an objective of general interest,” “establish clear and precise rules,” “ensure that the proceedings are coordinated,” and “ensure that the severity of all of the penalties imposed is limited to what is strictly necessary.” The Court also stated that this did not infringe on the European Convention on Human Rights because a state’s objectives of ensuring collection of all VAT due and guaranteeing the integrity of the EU’s financial markets justify the duplication of proceedings and penalties.

In Di Puma and Zecca, two cases regarding insider trading, the Italian courts asked whether national law conflicted with the EU directive concerning financial markets that requires member states to provide for effective, proportionate, and dissuasive penalties for infringements regarding insider dealing. Here, two parties received administrative penalties, but the criminal case that had been brought in parallel had found that insider trading was not established, and under Italian law and the principle of res judicata, an acquittal in a criminal case prohibits administrative proceedings on the same matter. The Court found that this legislation does not infringe EU law, both because of the importance of res judicata to EU law and because where there is an acquittal in a criminal case, bringing an administrative procedure infringes the ne bis in idem principle. Here, the Court held that bringing both such proceedings exceeds what is necessary to protect EU financial instruments.