The debate over protecting the environment has centered around whether and how wildlife should be utilized among preservationists and conservationists. While existing scholarship has mostly examined how the norm has emerged and developed over time, there is insufficient knowledge of how the meaning of the norm shifts and is reinterpreted after its emergence, particularly in the evolving context of norm contestation. By focusing on the listing and implementation of shortfin and longfin mako sharks in CITES Appendix II, I show how the meaning of sustainable use of wildlife is reinterpreted during the listing and implementing processes. Using process tracing and discourse analysis, I find that the CITES listing of mako sharks and the subsequent implementation processes did not simply extend a pre-existing conservation norm into international trade as a linear process. Instead, I see that it represents a continuous contestation over normative meaning as the norm was translated across different processes. This study contributes to the scholarship on norm diffusion by demonstrating how norm implementation occurs in a dynamic and non-linear process after its emergence.