Here we are not talking about applying a constitutional provision in a way consistent with the original public understanding of it (for example, by extending the First Amendment to television or the Fourth Amendment to electronic records). We are talking about applying a provision in a way the people who ratified it would have rejected. How can a right that was "unimagined" in this sense be a constitutional right?

According to the court, "equal protection can only be defined by the standards of each generation." But if the justices had defined equal protection by the standards of this generation (in Iowa, at least), they would have let the gay marriage ban stand.

"The point in time when the standard of equal protection finally takes a new form," the court said, "is a product of the conviction of one, or many, individuals that a particular grouping results in inequality and the ability of the judicial system to perform its constitutional role free from the influences that tend to make society's understanding of equal protection resistant to change." Let's be frank: Under this approach, it does not take "one, or many, individuals" to change the meaning of the constitution. It takes exactly four.

As the court noted, legislatures draw distinctions between groups all the time. They establish criminal penalties, impose age restrictions and set conditions for government benefits. If such policy judgments violate equal protection whenever four justices disagree with the reasoning behind them, the line between what judges do and what legislatures do begins to disappear.

Worse, this sort of result-oriented jurisprudence cannot be confined to decisions that limit government and expand freedom. If courts can reach "a new understanding of equal protection" that renders invalid heretofore constitutional laws, they also can reach a new understanding of the First Amendment, allowing restrictions on political speech in the name of fighting corruption, or the Commerce Clause, allowing the federal government to intervene in areas previously reserved to the states or the people.

In these and other cases, changing conditions are said to require reinterpretation, and since no constitution is perfect, you or I may occasionally like the results. But over the long term we cannot count on an evolving constitution to protect our rights.