“In any bureaucratic organization there will be two kinds of people: those who work to further the actual goals of the organization, and those who work for the organization itself. ... The Iron Law states that in all cases, the second type of person will always gain control of the organization...”
Iron Law of Bureaucracy
Pournelle’s law says that in any organization, the people who care about doing the actual work always lose control to the people who care about the organization itself. Schools are his prototype: teachers who care about kids lose to school administrators, education-school professors, and union officials. He runs the same diagnosis on NASA (engineers and scientists lose to headquarters staff) and on the old Soviet Union’s collective farms (agricultural scientists lose to the farming bureaucracy).
He first published the law in his Chaos Manor column View 406, April 3-9, 2006, with teachers vs. union representatives as the working example. (The file numbering on Pournelle’s site runs two ahead of the displayed view number; view408.html hosts View 406.) He restated it more fully in a 2010 essay that added the NASA and Soviet examples.
The mechanism is in the clause Pournelle attaches to the law: that second group “will always write the rules under which the organization functions.” Once you’re the one writing the promotion criteria, the people who keep getting promoted are the ones who care about your criteria. Run long enough, and the thing the organization was built to do becomes a side project; keeping the organization itself going becomes the main one.