Efforts in the field of the international unification of law have up until relatively recently tended to be concentrated essentially on initiatives designed to unify existing rules of domestic law concerning activities of sufficiently transnational importance as to make the absence of uniform international rules a major source of legal uncertainty for commercial parties contemplating engaging in such activities. This was notably the case with Unidroit's two 1964 Hague Conventions on the International Sale of Goods 1 and its 1983 Geneva Convention on Agency in the International Sale of Goods. One of the principal drawbacks to such efforts has naturally been the difficulty encountered in persuading States to give up this or that rule of their domestic law in favour of a new uniform rule. However, this difficulty is often as nothing compared to the problems that arise when it comes to such States deciding whether or not to ratify or accede to such Conventions. It is a fact that the most successful efforts in the field of the unification of law have often occurred in those areas where uniform law serves the dual function of providing a uniform international legal framework for international manifestations of a particular type of commercial activity and filling a legal vacuum regarding such activity at 398the domestic level. One of the most striking examples of such a phenomenon is the 1929 Warsaw Convention for the Unification of Certain Rules relating to International Carriage by Air, which, apart from governing international carriage by air for decades, has also provided the basis for the enactment of domestic carriage by air rules.