Abstract

Customs develop through established transactional practices and may supplement matters that are not addressed by the parties’ agreement or governed by applicable law. Although the 2015 Civil Code and the 2005 Commercial Law of Vietnam provide a legal basis for the application of customs in commercial activities, their provisions remain largely confined to general principles and do not comprehensively regulate the identification, invocation, proof, and assessment of customs. This article examines the concept, characteristics, functions, and limitations of legal customs; compares the Vietnamese legal framework with Article 9 of the 1980 United Nations Convention on Contracts for the International Sale of Goods and the UNIDROIT Principles of International Commercial Contracts; identifies practical difficulties arising from the application of customs; and proposes solutions to improve the mechanisms for identifying, proving, and applying customs in Vietnam.

Keywords: Commercial activities, dispute resolution, legal custom, practices established between the parties.