The current pattern of federal aid to education dates from passage of the Elementary and Secondary Education Act in 1965. Previous legislation had foundered in part on opposition from Catholics and others to aiding public schools without also aiding private schools. In ESEA it was agreed to extend the main form of aid to children in both. The question of how to deliver the aid without offending the Constitution was glossed over.

It was generally accepted that public funds could not be given directly to sectarian schools. The bill dodged by saying the main form of aid was to go to needy pupils. The legislation required public officials to provide equally for all such pupils in their districts, in private as well as public schools.

There are basically two ways to do this: move private-school children onto public turf for part of the day or, as carefully as possible, move publicly supported services into the private schools. For 20 years the latter has been the preferred alternative -- it's simpler. But last summer, in two 5-to-4 decisions, the Supreme Court struck it down. In the case of sectarian schools, the majority held there was no way to do it without impermissibly entangling church and state.

The decision produced some sharp dissents. "It borders on paranoia to perceive the Archbishop of Canterbury or the Bishop of Rome lurking behind programs" such as these, wrote Chief Justice Warren Burger. "I cannot join in striking down a program that, in the words of the Court of Appeals, 'has done so much good and little, if any, detectable harm.' "

The administration has also objected. Education Secretary William Bennett has made it clear that he will not let public officials back away from their statutory obligation to children in private schools. His department has sent guidance to state and local officials on how to comply -- for example, by providing services in mobile vans. Where then may such a van be parked? Certainly on public property, and "it is the view of the Department of Education that, under certain circumstances, mobile or portable units may constitutionally be placed on . . . private school property" as well.

It's a pretty long way from the majesty of the First Amendment to the designation of a parking space, and in some ways it trivializes government to have serious people grappling with distinctions such as this. But what are the alternatives? It is neither politically possible nor socially desirable to write private-school children out of the aid program. Everyone's favorite example: in a lot of cities a lot of poor black kids go to Catholic and other private schools. Who wants to shut them out? The administration would go to the other extreme and bypass the establishment clause by giving parents vouchers. That is money-laundering.

It is easy to mock where the court has brought us -- until you recall why. Justice William Brennan recalled in one of last year's cases: "For just as religion throughout history has provided spiritual comfort, guidance and inspiration to many, it can also serve powerfully to divide . . . and to exclude." Religion and government are a flammable combination. Park the vans across the street.