CFR›Title 50›Chapter II›Part 222›Subpart E ContainsSections 222.501–222.504CorpusDaily eCFRDisplayed edition2026-04-27Last updated2026-04-27 Subpart E—Experimental Populations Sections 222.501 § 222.501 Definitions. 222.502 § 222.502 Listing. 222.503 § 222.503 Prohibitions. 222.504 § 222.504 Interagency cooperation. Source81 FR 33421, May 26, 2016, unless otherwise noted. Previous D Subpart D—Observer Requirement