The push for greater clinical trial transparency is typically framed as a conflict between companies’ interest in protecting trade secrets and the public’s interest in accessing health-relevant information. But a new article by economists Dennis Byrski and Lucy Xiaolu Wang analyzes an underappreciated dimension of this debate: clinical trial disclosure also affects patenting. When trial data becomes public, it creates prior art that can block subsequent patents related to the drug. The authors document that European marketing authorization—which requires substantial data disclosure—leads to significant declines in secondary patenting on drug modifications like new dosages and formulations. The result is a regulatory check on pharmaceutical patent “evergreening”: once authorization-related disclosures enter the public domain, many incremental follow-on patents become harder to obtain.