https://www.archives.gov/federal-register/codification/executive-order/12333.html
"HOW DOES THE C_A COLLECT INTELLIGENCE?"
(g) Information arising out of a lawful personnel, physical or communications security investigation;
(h) Information acquired by overhead reconnaissance not directed at specific United States persons;
(i) Incidentally obtained information that may indicate involvement in activities that may violate federal, state, local or foreign laws; and
(j) Information necessary for administrative purposes.
In addition, agencies within the Intelligence Community may disseminate information, other than information derived from signals intelligence, to each appropriate agency within the Intelligence Community for purposes of allowing the recipient agency to determine whether the information is relevant to its responsibilities and can be retained by it.
2.4Collection Techniques. Agencies within the Intelligence Community shall use the least intrusive collection techniques feasible within the United States or directed against United States persons abroad. Agencies are not authorized to use such techniques as electronic surveillance, unconsented physical search, mail surveillance, physical surveillance, or monitoring devices unless they are in accordance with procedures established by the head of the agency concerned and approved by the Attorney General. Such procedures shall protect constitutional and other legal rights and limit use of such information to lawful governmental purposes. These procedures shall not authorize:
(a) The CIA to engage in electronic surveillance within the United States except for the purpose of training, testing, or conducting countermeasures to hostile electronic surveillance;
(b) Unconsented physical searches in the United States by agencies other than the FBI, except for:
(1) Searches by counterintelligence elements of the military services directed against military personnel within the United States or abroad for intelligence purposes, when authorized by a military commander empowered to approve physical searches for law enforcement purposes, based upon a finding of probable cause to believe that such persons are acting as agents of foreign powers; and
(2) Searches by CIA of personal property of non-United States persons lawfully in its possession.
(c) Physical surveillance of a United States person in the United States by agencies other than the FBI, except for:
(1) Physical surveillance of present or former employees, present or former intelligence agency contractors or their present of former employees, or applicants for any such employment or contracting; and
(2) Physical surveillance of a military person employed by a nonintelligence element of a military service.
(d) Physical surveillance of a United States person abroad to collect foreign intelligence, except to obtain significant information that cannot reasonably be acquired by other means.
2.5Attorney General Approval. The Attorney General hereby is delegated the power to approve the use for intelligence purposes, within the United States or against a United States person abroad, of any technique for which a warrant would be required if undertaken for law enforcement purposes, provided that such techniques shall not be undertaken unless the Attorney General has determined in each case that there is probable cause to believe that the technique is directed against a foreign power or an agent of a foreign power. Electronic surveillance, as defined in the Foreign Intelligence Surveillance Act of 1978, shall be conducted in accordance with that Act, as well as this Order.