Review Conferences have had a significant effect on the interpretation of the Biological Weapons Convention. Through Final Declarations the States Parties have developed and specified the Biological Weapons Convention, allowing for a more effective treaty. Several aspects of the Final Declarations can be considered as subsequent agreements for the purposes of treaty interpretation. On the basis of Article 31 Vienna Convention on the Law of Treaties, subsequent agreements are important aspects of treaty interpretation. The development of the Convention requires the continuous updating of the interpretation of the Convention and the lack of a comprehensive article-by-article discussion can create issues in the near future. However, regardless of its importance, it is necessary to retain the practice of consensus decision-making to ensure the retention of the Final Declaration’s status as authoritative interpretation. While there are risks with foregoing the Final Declaration for subsequent Review Conferences, the risk of fragmentation is of far greater consequence.