From the Document: "The Federal Vacancies Reform Act of 1998 (Vacancies Act) generally provides the exclusive means by which a government employee may temporarily perform the functions and duties of a vacant advice-and-consent position in an executive agency. [...] This report first describes how the Vacancies Act operates and outlines its scope, identifying when the Vacancies Act applies to a given office and which offices are exempt from its provisions. The report then explains who may serve as an acting officer and for how long, focusing on the limitations the Vacancies Act places on acting service. Next, the report discusses how the Vacancies Act is enforced. Finally, the report turns to evolving legal issues regarding the application of the Vacancies Act, including a discussion of how other federal laws may limit the Act's reach. Specifically, the report concludes by examining the interaction of the Vacancies Act with agency-specific statutes, the ability to delegate the duties of a vacant office, and constitutional considerations."
CRS Report for Congress, R44997
Congressional Research Service: https://crsreports.congress.gov/