5 C.F.R. § 2424.50 Illustrative criteria.
A compelling need exists for an agency rule or regulation concerning any condition of employment when the rule or regulation was issued by the agency or any primary national subdivision of the agency, and the agency demonstrates that the rule or regulation satisfies one of the following illustrative criteria:
(a) The rule or regulation is essential, as distinguished from helpful or desirable, to the accomplishment of the mission or the execution of functions of the agency or primary national subdivision in a manner that is consistent with the requirements of an effective and efficient government.
(b) The rule or regulation is necessary to ensure the maintenance of basic merit principles.
(c) The rule or regulation implements a mandate to the agency or primary national subdivision under law or other outside authority, which implementation is essentially nondiscretionary in nature.