Ne bis in idem is a fundamental principle which is enshrined in most legal systems, according to which a person cannot be punished more than once for the same (f)act. There are two main outstanding concerns with respect to that principle. First, the scope of the ne bis in idem principle to the various stages of the criminal procedure is subject to intense debate. Questions arise for example on the validity of a ne bis in idem objection when a decision has been taken not to prosecute the person for the said (f)act.
Second, even though numerous international instruments refer to the principle, the ‘international’ character (i.e. cross-border applicability) of the principle is far from generally accepted and applied. Ne bis is most commonly interpreted in a mere domestic context, i.e. as a limit to proceedings in the same member state. This contribution looks into these main concerns and elaborates on a number of recommendations to elaborate a comprehensive and consistent EU ne bis policy. In doing so, the EU policy could develop from a diversified present to a coherent future. The authors come to the conclusion that (1) there is a need for an unambiguous definition of the situations that can give rise to a ne bis in idem obstacle, combined with (2) consistency regarding the mandatory or optional character thereof. Additionally, to ensure a cross-border application of the principle, there is a need to (3) agree on a set of minimum standards, possibly combined with (4) a decision making role for Eurojust.