What ought to count is whether a legal opinion offers the most compelling view of the Constitution in light of its text, history, prior judicial interpretation, and current understanding of the country's needs.
He loathes the idea of the so-called "living Constitution," the idea behind many of the Warren Court's decisions, which essentially says that values evolve and change, and we have to interpret the great precepts of the Constitution in light of those changes.
This view was in sharp contrast to the judicial liberalism that was dominant when Chief Justice Rehnquist came of age as a young lawyer, when the federal courts were thought to have -- or behaved as if they had -- an almost oracular ability to discern the hidden meaning of the Constitution in light of the public good.
Second, the justice would "interpret the Constitution in light of the entire history of the nation, and not just in light of the Constitution's drafting history".
And a book he co-wrote argues that judges should interpret the Constitution "in light of the concerns, conditions and evolving norms of our society" — an approach some conservatives say enables judges to impose their own political values.
It's not surprising that he indicts liberal justices like William Brennan for embracing a theory of living constitutionalism that "led the courts deep into the thickets of abortion, capital punishment and habeas corpus" by encouraging them to update the Constitution in light of contemporary values.
In this society, it is the Supreme Court that has the responsibility to interpret the Constitution in light of changing realities.
But the collection of this data also enables speed-of-light violations of the Constitution.
The Thirteenth Amendment, which abolished slavery, represents an updating of the Constitution in the light of history and experience.
But, argues Mr Koh, they interpret the constitution in the light of international, not just American, norms.
