Montesquieu's Mistakes and the True Meaning of Separation

In The Spirit of the Laws, Montesquieu concluded that a constitutionof liberty could best be achieved, and had been achieved inBritain, by assigning three essentially different governmentalactivities to different actors. He was wrong. His mistaken conclusionrested on two errors. First, Montesquieu thought that the primaryexercise of powers could durably be divided only where thosepowers differed in kind. Second, Montesquieu failed to recognizethe lawmaking character of executive and judicial expositionof existing law. This article analyzes implications of Montesquieu’smistakes for modern claims, both in Britain and in the UnitedStates, that liberty and the rule of law are promoted by separatingpower in certain contexts. In particular, this article questionsthe British Government’s recent claim that the valuesunderlying separation-of-powers theory call for removing ultimateappellate jurisdiction from the House of Lords. It also tracesMontesquieu’s influence on the American founders’attempt to separate power along essentialist lines, and considerssome sub-optimal consequences of that attempt, including thenon-delegation quandary and the emergence of an unchecked judiciallawmaker.