Code of Federal Regulations45 CFR 46 (Title 45, Subchapter A, Part 46 of the Code of Federal Regulations) is also known as the Common Rule. This regulation defines the U.S. HHS policy regarding the protection of human subjects in research, and includes protections for vulnerable populations such as pregnant women, children, and prisoners. The CFR also defines the protection of human subjects for other federal agencies, which can be found through searching this page.