During the hiatus between Supreme Court confirmation battles, we may as well settle the clash between the conservative and liberal approaches to constitutional interpretation. The battle lines are familiar. Conservatives, led by Justices Antonin Scalia and Clarence Thomas, say that the sole legitimate approach is to follow the literal text and original meaning of constitutional provisions and amendments. Justices’ policy preferences should play no role, assert conservative "originalists." But the claim is undercut somewhat by the consistency with which the conservatives’ votes on abortion, religion, race, gay rights, and many other big issues happen to fit their policy preferences.

Liberals and many moderates prefer the "living-Constitution" approach, which has been dominant at least since the Warren Court. It involves using ancient but conveniently vague constitutional phrases to enforce "evolving standards of decency," to promote equality, and to vindicate what sometimes-liberal Justice Anthony Kennedy likes to call "the right to define one’s own concept of existence, of meaning, of the universe, and of the mystery of human life." Not surprisingly, constitutional evolution in the hands of liberals supports liberal policies.

Each school of thought is most persuasive in debunking the other. Justice Stephen Breyer skewers originalism in his 2005 book, Active Liberty: "Why would the Framers, who disagreed even about the necessity of including a Bill of Rights in the Constitution, who disagreed about the content of the Bill of Rights, nonetheless have agreed about what school of interpretive thought should prove dominant in interpreting the Bill of Rights in the centuries to come?"

Even when the original meaning is undisputed, it is often intolerable to conservatives as well as liberals. Many Framers did not see the flogging or even the execution of a 12-year-old for theft as "cruel and unusual punishment," for example. And nothing in the text or original meaning of the Constitution was designed to bar the federal government from discriminating based on race (or sex). This has not stopped Scalia or Thomas from voting to strike down federal racial preferences for minorities. Nor have they hesitated to invoke debatable interpretations of the Constitution to attack laws regulating campaign finance and imposing monetary liability on state governments.

The living-Constitution approach may be even more problematic, because it has cut a wider swath through democratic governance with even less basis in the written Constitution.

If the Constitution is an "invitation to apply current societal values," as Scalia has asked, "what reason would there be to believe that the invitation was addressed to the courts rather than to the legislature? … A democratic society does not, by and large, need constitutional guarantees to ensure that its laws will reflect ‘current values.’ Elections take care of that."