Implementation performance in the field of the EU Customs Union: consequences of differentiated policy implementation on customs control efficiency

Research in differentiated policy implementation in the European Union is in vogue because of its strengths for deploying public policies and assessing policy outcomes. This article sets out a path dependency argument about the dynamics of differentiated customs policy implementation in the EU. We analyse two highly representative cases of customs fraud to develop a quantitative and qualitative approach to the impact of customisation on customs control performance: the first, linked to an exercise of unfair competition; the second, a case of customs common standards 'misinterpretation' related to path dependency. We conclude that differentiated policy implementation has proved inefficient for ensuring an equivalent level playing field of customs controls in the EU, resulting in three substantial negative outcomes: economic and budgetary; problem-solving capacity; and output legitimacy. Differentiated policy implementation can lead to a competitive disadvantage, especially when dealing with policies that do not permit any graduation in their fulfilment.