Why is it difficult to create worldwide uniform rules for international sales contracts?

Creating worldwide uniform rules for international sales contracts is difficult primarily because of the significant divergences in national sales laws. While there is a strong demand for legal certainty in international trade, achieving global uniformity faces several structural and practical obstacles.12

• Legal Diversity: Substantive laws vary widely across jurisdictions. Establishing a uniform body of rules is most successful when participating communities already share similar legal principles; achieving this on a global scale is far more complex than doing so within a single nation, such as the United States with its Uniform Commercial Code.3
• Limited Participation and Interpretation: Even when international conventions are adopted, they often involve only a small number of states. Furthermore, the interpretation and application of these treaties remain the responsibility of individual national courts, which can lead to inconsistent outcomes.4
• Mandatory National Rules: Many form contracts attempt to bridge these gaps, but they cannot override the mandatory rules of national law, limiting their effectiveness.1
• Sovereignty and Conflicts: Because conflicts law is part of national legal systems rather than a codified supranational system, countries often rely on their own criteria to determine which law applies to a transaction, further complicating the path to a single, worldwide standard.45