Article 6(3) of the Convention of 27 September 1968 on Jurisdiction and the Enforcement of Judgments in Civil and Commercial Matters, as amended by the Convention of 9 October 1978 on the Accession of the Kingdom of Denmark, Ireland and the United Kingdom of Great Britain and Northern Ireland and by the Convention of 25 October 1982 on the Accession of the Hellenic Republic, applies only to claims by defendants which seek the pronouncement of a separate judgment or decree. It does not apply to the situation where a defendant raises, as a pure defence, a claim which he allegedly has against the plaintiff. The defences which may be raised and the conditions under which they may be raised are governed by national law.