Ensuring that civil service bureaucracies respond to changing political preferences is a democratic imperative. Thomas Elston and a colleague have published an article in the Journal of Public Administration Research and Theory on what enables civil services to implement decisions by politicians. 

Better-resourced bureaucracies are more likely to be able to implement decisions, but the authors find that, more specifically, civil services need to have slack in the system: capacity beyond current operational requirements. Otherwise, so much capacity is sunk into implementing prior policy commitments that new political signals are not acted upon.