Wonder how it's decided? I'll bet NO REPUBLCANS have been in included in THAT decision.
52. Why do some federal employees continue to work during a shutdown? The law — or at least, the Justice Department's interpretation of it — contains exemptions for several classes of employees: The biggest exemption is for employees necessary to protect public health, safety or property. But property could include government data, ongoing research experiments or other intangibles. Political appointees are exempt because they cannot be placed on leave by law. Employees necessary for the president to carry out his constitutional responsibilities are exempt. Finally, employees whose salaries are paid from sources outside an annual spending bill can still get paid and report to work.
53. Who decides which employees work and which go home? Each agency is responsible for coming up with its own contingency plan, based on guidance from the Office of Management and Budget and the Office of Personnel Management. Those plans are then sent to the White House for review.(links to guidelines at above)