› ohrp › regulations-and-policy45 CFR 46 | HHS.gov The HHS regulations for the protection of human subjects in research at 45CFR 46 include five subparts. Subpart A, also known as the Common Rule, provides a robust set of protections for research subjects; subparts B, C, and D provide additional protections for certain populations in research; and subpart E provides requirements for IRB registration.