An EU directive does not immediately have the force of law in our domestic law. Implementing legislation is required in the UK parliament to give effect to the directive. But what happens if the UK parliament fails to implement a directive properly? Broadly,
(a)the victim can rely upon the directive if he is suing part of the state for causing him personal injury;
(b) as against another private individual the victim cannot rely upon the directive but may be able to persuade the courts to interpret the domestic legislation in a way that is in compliance with the directive
(a) if all else fails the victim can sue the government for damages for failure to implement the directive properly.
The main principles are helpfully collated in Dominguez v Centre Informatique du Centre Ouest Atlantique and another (Case C-282/10)  2 C.M.L.R. 14 (ECJ)
1. The principle that domestic law has to be interpreted in conformity with EU law also requires national courts to do whatever lay within their jurisdiction with a view to ensuring that the Directive in question was fully effective and achieving an outcome consistent with the objective pursued by it. In order to do this the courts should take the whole body of domestic law into consideration and apply the interpretive methods recognised by domestic law.
2. If the provisions of a Directive appear to be unconditional and sufficiently precise, they might be relied upon before the domestic courts by individuals against the Member State where the latter had failed to implement the Directive in domestic law by the end of the period prescribed or where it had failed to implement the Directive correctly.
3. A Directive cannot of itself impose obligations on an individual and cannot therefore be relied on as such against an individual. However, as against an individual but as against the state, a person may rely upon the Directive regardless of the capacity in which the Member State was acting when it is said to have breached the terms of the Directive. This is so whether the state was acting as an employer or as a public authority. The reason for this is to prevent the Member State from taking advantage of its own failure to comply with EU law.
4. Where the provisions of a Directive were capable of having direct effect, the entities caught by that effect included a body which had been made responsible for providing a public service under the control of the State. The reason for this is that such a body had for that purpose special powers beyond those which resulted from the normal rules applicable in relations between individuals.
5. Even a clear, precise and unconditional provision of a Directive seeking to confer rights or impose obligations on individuals could not of itself apply in proceedings exclusively between private parties under the doctrine of direct effect. In such a situation, the party injured as a result of the domestic law not being in conformity with EU law could nonetheless rely on the judgment in Francovich v Italy (C-6/90 & C-9/90)  E.C.R. I-5357; in order to obtain compensation from the Member State for the loss sustained.
6. The purpose of many health and safety directives was to lay down minimum safety and health requirements. As such these do not affect the right of Member States to apply national provisions which result in more protection for workers.