According to the Court of Justice, in its judgment of 27 March 1963, in Joined Cases 28, 29, 30/62, Da Costa en Schaake NV and Others/Nederlandse Belastingadministratie, the obligation imposed by the third paragraph of Article 177 of the EEC Treaty (now Article 234 of the EC Treaty) upon national courts or tribunals of last instance may be deprived of its purpose by reason of the authority of an interpretation already given by the Court under the said Article in those cases in which the question raised is materially identical with a question which has already been the subject of a preliminary ruling in a similar case.