The Certificate of Confidentiality (Certificate) is an important tool for protecting identifiable, sensitive human subjects research data in the United States. However, little is known about the Certificate’s effectiveness in protecting identifiable data. We interviewed 24 legal counsel representing U.S. research institutions about their experiences with legal demands for research data. Our respondents reported few, if any, legal demands over the course of their tenure, but two- thirds had experience with legal demands for data protected by a Certificate. They reported such demands often were resolved without disclosure of identifiable research data, typically without court intervention. While our respondents reported similar success protecting identifiable data in court, they often did not rely on the Certificate to do so.