Private international law and the difficult problem to return illegally exported cultural property

Many countries prohibit the exportation of national cultural treasures without government permission. These countries may enforce this obligation within their territory, but they cannot enforce it abroad, when the object has left the country of origin. In the importing country, the foreign export prohibition, being an obligation of public law, cannot be enforced by the country of origin, and also the conflict of laws rules of the importing country will not directly enforce this prohibition as foreign public law. This is recognized not only in the United Kingdom but everywhere and can only be changed by an international instrument providing for the application of foreign public law. If there is no international instrument, foreign States try to enforce their ownership rights that they may have under local patrimony laws. Foreign export prohibitions may, however, be given effect indirectly by the applicable national private law. These foreign prohibitions are not local prohibitions invalidating a contract because overriding mandatory provisions of the lex fori have been violated, but they may invalidate a contract because good morals have been violated. There is no general international instrument invalidating legal transactions violating foreign export prohibitions. States have to apply Article 7 of the Rome Convention of 1980 or Article 9 of the Rome I Regulation on a case-by- case basis.