The rule of law means that government must never coerce an individual except in the enforcement of a known rule, it constitutes a limitation on the powers of all government, including the powers of the legislature.
—Friedrich Hayek. The Constitution of Liberty, 1960.
Government officials are not holders of a privilege whereby they can do anything they want provided it is not expressly prohibited. Rather, the opposite is true—in their official capacity, they must only do what is expressly authorized by the law. Everything else is illegal. As John Trenchard explained: “When he exceeds his commission, his acts are as extrajudicial as are those of any private officer usurping an unlawful authority, that is, they are void; and every man is answerable for the wrong which he does.” (Cato’s Letters No. 59, Liberty proved to be the unalienable right of all mankind, Saturday, December 30, 1721.)
This doctrine prevents executive or bureaucratic officials from pursuing any agenda other than ensuring that the law is obeyed and the public service operates efficiently. It is this crucial limitation that makes the ‘rule’ of such officials benign.