There is a saying in Washington that “personnel is policy.” For better or worse, that saying applies especially to the Supreme Court, whose nine life-tenured justices have the final word on questions of federal law. We will soon be facing an important moment in the court's—and our country's—history. The next president will replace at least three justices: Chief Justice William Rehnquist, and Associate Justices Sandra Day O'Connor and John Paul Stevens, all of whom are widely expected to retire within the next four years.

This is a prospect that has not received the attention it deserves, perhaps because much of the public still assumes that the Supreme Court is just a bunch of legal technocrats, dryly opining on abstract legal questions. Now, if that were true, if the Supreme Court really did just practice law in a dispassionate way, then replacing retiring justices would not be a particularly momentous occasion. And the public could safely be bored with it. The reality, however, is very different.

The Supreme Court has long been divided, not only over what individual constitutional provisions mean, but more fundamentally, over how to decide what they mean. Some justices take the strict view that the Constitution's language still means only what it originally meant, no more and no less. Others give themselves wide latitude to read new and evolving meanings into it. The resulting conflict means that the personalities of the Supreme Court justices end up determining much of what the Constitution requires. So whenever one-third of these personalities turns over, it is a significant event. That would be true no matter which three justices were retiring. But the fact that it is these three in particular makes the event truly critical.

Consider, for example, the potential effects on issues of religious liberty.

Common sense is only just starting to return to the law of religious liberty. Beginning in the 1940s a majority of the Supreme Court held that the First Amendment required the government not only to be neutral among individual religions, that is, to treat Baptists the same way it treats Catholics and Jews, but that it also required the government to be neutral between religion and what some justices called “irreligion.” That was a critical mistake. It effectively dispatched lower level officials on a search-and-destroy mission against all expressions of religion in public life. Then, to add insult to injury, a majority of the Supreme Court consistently refused to apply neutrality evenhandedly. Just as in George Orwell's Animal Farm, where some animals were “more equal” than others, some laws, notably those that disadvantaged religious institutions, were “more neutral” than others. Religion almost always lost.

The departure of these three justices will be a truly critical event.

In the 1980s, however, that began to change—because the court's personnel began to change. A majority of the court still clung to its mistaken view that the First Amendment required neutrality between religion and irreligion, but at least neutrality began to be neutral. The court, for example, held that government benefits could aid both religious and nonreligious institutions equally. This was a great step forward. One result was that parochial school students entitled to government financial remedial instruction could now receive that tutoring inside their classrooms, just like everybody else. Under the Supreme Court's prior interpretation, the kids had to leave their school buildings and be tutored in vans parked on the street.

The court also held that private religious expression was almost as welcome in the public square as other types of private speech. This was a great half-step forward. In a case called Capitol Square vs. Pinette the court held that the grounds of the Ohio State Capitol, which were open on a first-come-first-served basis for private displays, could not be closed to a group who wanted to display a cross. Nevertheless, a bare majority of the justices refused to make that rule categorical. They took the extraordinary view that there might arise in the future a situation where private religious speech would have to be discriminated against to keep the public from mistaking it for government speech.

In short, the law of religious liberty is better than it used to be, but still a far cry from what it should be.

It is also very tenuous. In both the education case and the cross case, the 5-4 margin of victory was provided by two of the three justices who will be replaced by the next president. In the education case, it was Chief Justice Rehnquist and Justice O'Connor who provided the majzority to vindicate religious liberty. In the cross case it was Justice O'Connor and Justice Stevens who rounded out the five-vote majority and left a cloud hanging over religious speech. The three of them have been responsible for many other 5-4 cases as well.

In short, all of the religious liberty gains that have been achieved to date, and all of the potential gains for the future, depend on whom the next president appoints to replace Chief Justice Rehnquist, Justice Stevens and Justice O'Connor. It is a shame that the Supreme Court is so politicized. But until that changes, the president's personnel decisions will determine the shape of our constitutional rights.

Kevin J. Hasson is president and general counsel of the Becket Fund for Religious Liberty in Washington, D.C.