A. V. Dicey Quote

The fact that the most arbitrary powers of the English executive must always be exercised under Act of Parliament places the government, even when armed with the widest authority, under the supervision, so to speak, of the Courts. Powers, however extraordinary, which are conferred or sanctioned by statute, are never really unlimited, for they are confined by the words of the Act itself, and, what is more, by the interpretation put upon the statute by the judges. Parliament is supreme legislator, but from the moment Parliament has uttered its will as lawgiver, that will becomes subject to the interpretation put upon it by the judges of the land.

Introduction to the Study of the Law of the Constitution [Eighth Edition, 1915] (LibertyClassics, 1982), p. 273.