provinces. At the international level, it is expressly rejected by the UNIDROIT Principles of International Commercial Contracts on the grounds that it yields uncertainty and unnecessary litigation, thereby hindering international trade. Similarly, the United Nations Convention on Contracts for the International Sale of Goods does not require consideration for a contract to be valid, thereby excluding the doctrine with regard to contracts covered by the convention even in common law jurisdictions where it would otherwise apply. Consequently, the continued existence of the doctrine in common law jurisdictions is controversial. In Canadian common law jurisdictions, like in England and Wales but unlike in India, the performance of pre-existing duties has not traditionally been regarded as good consideration. This can create uncertainty where parties to a contract agree to amend its terms after it has been concluded since such post-contractual modifications may run afoul of the requirement for fresh consideration. Court rulings in New Brunswick and British Columbia have abrogated this rule with regard to post-contractual modifications, while courts in Ontario have continued to require fresh consideration. Contracts for the International Sale of Goods In Canada, as in the vast majority of jurisdictions, the Convention on Contracts for the International Sale of Goods (CISG) governs contracts concerning the international sale of goods. The CISG facilitates international trade by removing legal barriers among state parties (known as "Contracting States") and providing uniform rules that govern most aspects of a commercial transactions, such as contract formation, the means of delivery, parties' obligations, and remedies for breach of contract. Unless expressly excluded by the contract, the convention is automatically incorporated into the domestic laws of Contracting States. Consequently, the criteria for the creation of contracts for the international sale of goods are substantially harmonised among civil, common, and mixed law jurisdictions around the world. The CISG applies to contracts of the sale of goods between parties whose places of business are in different States, when the States are Contracting States (United Nations Convention on Contracts for the International Sale of Goods, Article 1(1)(a)). Given the significant number of Contracting States, this is the usual path to the CISG's applicability. The CISG also applies if the parties are situated in different countries (which need not be Contracting States) and the conflict of law rules lead to the application of the law of a Contracting State. For example, a contract between a Japanese trader and a Brazilian