Popitz's law
The Popitzsche law of the attracting force of the central budget (by John Popitz ) represents a correlation between the increase in the state ratio over time and the increase in the proportion of the central government the entire state issues forth. A service provided further down in the hierarchy (federal, state, local etc.) shifts further up over time.
causes
Only the central state can ensure equality within the regions of the state. Also, only the central government is authorized to act in the event of a crisis with regard to tax powers.
Another reason for the validity of the law is that civil servants no longer want to relinquish powers once they have acquired them for career reasons.
Empiricism
When reviewing the law, problems arise, especially because higher hierarchical levels often make decisions that also affect lower levels.