What is indirect effect of EU law? The doctrine of indirect effect, or consistent interpretation, is a duty that national courts have, as part of the Member State responsible for fulfilment of EU obligations, to interpret national law in light of EU law, especially with Directives. It achieves indirectly, via judicial interpretation of national law, the result obtainable through direct effect of Directives where that principle cannot be applied. The principle was developed by the Court of Justice in Von Colson and its scope was widened in Marleasing. It is also a means to counteract, at least partially, the negative effects of the non-recognition of horizontal direct effect of Directives. For background reading, see Practice Note: Direct effect of EU law. The Von Colson case was a referral for a preliminary ruling on the interpretation of Directive 76/207/EEC on the implementation of the principle of equal treatment for men and women as regards access to employment, vocational training and promotion, and working conditions. The national litigation concerned alleged discrimination suffered by qualified social workers