A mixed system means any system of records that collects, maintains, or disseminates information, which is in an identifiable form, and which contains information about U.S. persons and non-U.S. persons.
The mixed system policy is applied consistent with the Privacy Act's inapplicability to intelligence files and data systems devoted solely to foreign nationals or maintained for the purpose of intelligence activities made subject to the provisions and protections of Executive Order 12333. The mixed system policy does not establish a right of judicial review for nonresident aliens.
Section 2.3 of Executive Order 12333 permits elements of the Intelligence Community to collect, retain, or disseminate information concerning U.S persons, which includes both U.S. citizens and legal permanent residents, but only in accordance with specific implementing procedures. Within DHS, these procedures require personnel to exercise due diligence in determining whether or not the subject of the intelligence is a U.S. person. When DHS conducts the necessary due diligence to identify whether or not the information in its intelligence systems is about a U.S. person, such systems are not considered mixed systems.