17This diversity between national systems derives mainly from the lack of Community rules on the refund of national charges levied though not due. In such circumstances, it is for the domestic legal system of each Member State to designate the courts and tribunals having jurisdiction and to lay down the detailed procedural rules governing actions for safeguarding rights which individuals derive from Community law, provided, first, that such rules are not less favourable than those governing similar domestic actions (principle of equivalence) and, second, that they do not render virtually impossible or excessively difficult the exercise of rights conferred by Community law (principle of effectiveness) (see, in particular, Case C-231/96 Edis [1998] ECR I-4951, paragraph 34).
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