Artikel 13

Where the régime applicable to any class of imported goods depends on the fulfilment of particular technical conditions as to their constitution, purity, quality, sanitary condition, district of production, or other similar matters, the Contracting States will endeavour to conclude agreements under which certificates, stamps or marks given or affixed in the exporting country to guarantee the satisfaction of the said conditions will be accepted without the goods being subjected to a second analysis or other test in the country of importation, subject to special guarantees to be taken where there is a presumption that the required conditions are not fulfilled. The importing State should be afforded every guarantee as to the authorities appointed to issue the certificates and the nature and standard of the tests applied in the exporting country. The Customs administrations of the importing State should also retain the right to make a second analysis whenever there are special reasons for doing so.
To facilitate the general adoption of such agreements, it would be useful that they should indicate:
(a) The methods to be uniformly adopted by all laboratories appointed to make analyses or other tests, these methods being open to revision from time to time at the request of one or more of the States parties to such agreements;
(b) The nature and standard of the tests to be carried out in each of the States parties to such agreements, due care being taken that the standard of purity required for the various products is fixed in such a way as not to be tantamount to virtual prohibition.