A:
In 1993, Deputy Secretary of Defense William Perry issued a memorandum on "Chemical Weapons Research Programs Using Human Test Subjects." The memorandum released "any individuals who participated in testing, production, transportation or storage associated with any chemical weapons research conducted prior to 1968 from any non-disclosure restrictions or written or oral prohibitions (e.g., oaths of secrecy) that may have been placed on them concerning their possible exposure to any chemical weapons agents."
Secretary Perry also directed the Services to initiate procedures to release individuals who participated in testing, production, transportation or storage associated with any chemical weapons research after 1968 from any non-disclosure restrictions that may have been placed on them. Since most information relating to this research has been declassified, at least in part, Force Health Protection and Readiness has determined that participants in chemical-related research after 1968 may talk about their individual experiences to the Department of Defense (DoD) or the Department of Veterans Affairs without violating their oath of secrecy.
In January 2011, another memo, "Release from Secrecy Oaths Under Chem-Bio Research Programs", was released. This new memo clarifies and expands the 1993 directive to include biological weapons test subjects.