We tend to think of Supreme Court decisions as watermarks showing the state of the culture. We oughtn't. The latest Supreme Court decisions don't tell us what society is like now. Rather, they paint a powerful picture of what America's future might look like.

That's because the law is a great teacher. If the law limited itself to being a definition of the boundaries we would set on our own, it would fail its purpose.

Laws against speeding, trespassing and pollution impose standards we wouldn't naturally make on our own. Left to our own devices, we'd drive 80 miles per hour, boat and fish in the reservoir, and not notice so much where we left our trash. But the law helps teach us important lessons: Watch out for others, be aware of property lines, respect the environment.

This is what's wrong with the Supreme Court's decision to decriminalize sodomy. If put to a vote, polls suggest that Americans would likely make the most extreme forms of sodomy illegal. That means that the Supreme Court isn't using its boundary-defining powers to accept sodomy — it's using its teaching power to encourage sodomy.

The court isn't saying, “I suppose you're right. Extreme forms of sodomy are okay.” It's saying, “Sodomy is a good thing. Reconsider it.”

While we're on the subject, if we thought of Supreme Court decisions as lessons about the culture, we might read the decision about allowing library pornography filters with a sigh of relief.

But look at Supreme Court decisions as signs of what behaviors elites want to encourage, and the relief disappears.

How relieving is it that the National Librarians Association and other powerful elites fought all the way to the highest court in the land to keep pornography available in public libraries? How relieving is it that a third of the Supreme Court saw no problem with allowing unrestricted access to pornography at the audio-visual station next to the story-time room?

Or leave children out of it for a moment. Why should pornography be allowed for anyone at allin a public library? Librarians have sued for sexual harassment because they were being forced by patrons to see pornography.

Of course libraries must block pornography. What's there for the Supreme Court of the United States to deliberate in that?

The problem is that Supreme Court decisions are self-fulfilling prophecies. Take abortion. It was repugnant to the vast majority of Americans before it was legalized. Now it's the most common surgical procedure performed on young women. What will happen now that the Supreme Court is teaching that sodomy is normal?

The court's majority opinion tsk-tsked that sodomy laws “seek to control a personal relationship that, whether or not entitled to formal recognition in the law, is within the liberty of persons to choose without being punished as criminals.”

It continued, in teaching language: “This, as a general rule, should counsel against attempts by the state, or a court, to define the meaning of the relationship or to set its boundaries absent injury to a person or abuse of an institution the law protects.”

In other words, in removing the boundary to sodomy, the Supreme Court taught that communities can't criminalize consensual sexual activity.

Really? Then what's to stop legal incest, adultery, polygamy, bigamy and prostitution? And how long will take for the full implications of that teaching to be realized?

It is not too hard to look down the road and see the Supreme Court recognizing that it shouldn't define the meaning of the marital relationship either.

Absent any serious movement to protect marriage, that's exactly what will happen. Then John Paul's prophetic words will haunt our currently complacent Catholic families: “Families will be the first victims of the evils that they have done no more than note with indifference” (Familiaris Consortio, No. 44).