Types of Information DOD May Collect on US persons

"C2.3 TYPES OF INFORMATION THAT MAY BE COLLECTED ABOUT UNITED STATES PERSONS,
"Information that identifies a United States person may be collected by a DoD intelligence component only if it is necessary to the conduct of a function assigned the collecting component, and only if it falls within one of the following categories:
"C2.3.1. Information Obtained With Consent. Information may be collected about a United States person who consents to such collection.
"C2.3.2. Publicly Available Information. Information may be collected about a United States person if it is publicly available.
"C2.3.10. Narcotics. Information may be collected about a United States person who is reasonably believed to be engaged in international narcotics activities."

Source: 

Under Secretary of Defense for Policy, "Procedures Governing the Activities of DOD Intelligence Components That Affect United States Persons," (Washington, DC: United States Department of Defense, December 1982), p. 17.
http://www.fas.org/irp/doddir/...