What is Constitutionalism?

From Charles Krauthammer here:

Call it constitutionalism. In essence, constitutionalism is the intellectual counterpart and spiritual progeny of the "originalism" movement in jurisprudence. Judicial "originalists" (led by Antonin Scalia and other notable conservative jurists) insist that legal interpretation be bound by the text of the Constitution as understood by those who wrote it and their contemporaries. Originalism has grown to become the major challenger to the liberal "living Constitution" school, under which high courts are channelers of the spirit of the age, free to create new constitutional principles accordingly.

What originalism is to jurisprudence, constitutionalism is to governance: a call for restraint rooted in constitutional text. Constitutionalism as a political philosophy represents a reformed, self-regulating conservatism that bases its call for minimalist government - for reining in the willfulness of presidents and legislatures - in the words and meaning of the Constitution.