AC-3(4) — Discretionary Access Control

Supplemental Guidance

When discretionary access control policies are implemented, subjects are not constrained with regard to what actions they can take with information for which they have already been granted access. Thus, subjects that have been granted access to information are not prevented from passing the information to other subjects or objects (i.e., subjects have the discretion to pass). Discretionary access control can operate in conjunction with mandatory access control as described in [AC-3(3)](#ac-3.3) and [AC-3(15)](#ac-3.15) . A subject that is constrained in its operation by mandatory access control policies can still operate under the less rigorous constraints of discretionary access control. Therefore, while [AC-3(3)](#ac-3.3) imposes constraints that prevent a subject from passing information to another subject operating at a different impact or classification level, [AC-3(4)](#ac-3.4) permits the subject to pass the information to any subject at the same impact or classification level. The policy is bounded by the system. Once the information is passed outside of system control, additional means may be required to ensure that the constraints remain in effect. While traditional definitions of discretionary access control require identity-based access control, that limitation is not required for this particular use of discretionary access control.