28 CFR 17.44: Access eligibility.
(a) Determinations of eligibility for access to classified information are separate from suitability determinations with respect to the hiring or retention of persons for employment by the Department or any other personnel actions.
(b) The number of employees eligible for access to classified information shall be kept to the minimum required for the conduct of Department functions.
(c) Eligibility for access to classified information shall be limited to classification levels for which there is a need for access. No person shall be granted eligibility higher than his or her need.