The terms of the judgment left open to argument the question of whether this interpretative obligation applied to national law generally, or only to national law specifically designed to implement a directive. Advocate General Van Gerven has raised the further possibility that the interpretative obligation should apply from the moment the directive comes into force, albeit without expressing a decided view on the matter. As a matter of Community law, it is permissible to interpret national law so as to give effect to a directive where to do so would infringe a superior rule of Community law. The English courts unfortunately have provided little constructive guidance as to when domestic law is “open” to interpretation consistent with Community law. It is only open where “it is reasonably capable” of bearing a construction that is consistent with Community law. The justification for this is that in such cases “it is of particular importance to ascertain the true purpose of the statute”.