Since 2009, the choice of law rule for individual employment contracts is unified by the EU's Rome I regulation. However, national courts may offer a higher protection by applying national laws considered to be particularly important as "overriding mandatory rules" or discard foreign law regarded as contrary to their "public policy." The study analyses the different evolutions in Germany and France and looks at the impact of the Europeanization between unification and plurality, predictability of court decisions and the need to ensure that justice is done in each individual case. The analysis focuses on the criteria which may help to identify overriding mandatory rules and principles of public policy. It develops a differentiated approach of interpreting and applying the Rome I regulation in the light of social rights enshrined especially in the EU Charter of Fundamental Rights. This may lead to the mandatory application of a minimum protection in cross-border employment relationships.