Bad break for public schools

Americans who vigorously support separation of church and state will feel concerned about the Supreme Court ruling backing a state tax deduction for private - and public - school costs. On the face of it, the ruling seems to let down the judicial guard on this important First Amendment issue.

But that is not necessarily so. In this case the high court argued that because a Minnesota law allowing a tax deduction for educational expenses applied to public as well as private schools the law was not unconstitutional - even though most of the tax benefits would go to parents with children in parochial schools. Said Justice William Rehnquist: ''A program that neutrally provides state assistance to a broad spectrum of citizens is not readily subject to challenge'' under the First Amendment establishment clause. It is significant , however, that the court let stand a 10-year-old decision which declared unconstitutionalm a New York tax credit plan that applied only to private and parochial schools.

So it is not clear whether the ruling helps the President's efforts to push through a federal tuition tax credit plan. That plan, which has cleared a Senate committee, covers only private schools. It would therefore seem to risk judicial challenge unless it were broadened to include public schools.

In any case, the closeness of the decision in the Minnesota case - the court ruled 5 to 4 - suggests a wide latitude for argument. Certainly many Minnesota parents with children in elementary and secondary public schools will feel an injustice in the ruling inasmuch as the net effect is to benefit private education. Theoretically, they can deduct up to $700 per child for the cost of public schooling. But those expenses are minimal. It is the private schools which have the preponderant cost, i.e., tuition. In Minnesota, moreover, most of the independent schools are sectarian.

Those who dissented with the opinion in fact argued that the Minnesota law has the direct result of promoting religion. Justice Thurgood Marshall wrote that the statute, by ensuring that parents will receive relief for tuition payments, requires that all taxpayers pay for the cost of parochial education and ''extends a financial incentive to parents to send their children to sectarian schools.''

The law, he said, ''is little more than a subsidy of tuition masquerading as a subsidy of general educational expenses.''

Will some states, under pressure from religious and other independent schools , now feel less reluctant to adopt tax-deduction or tax-credit plans as long as they cover all parents? Even if such plans are deemed constitutional, it does not mean they are wise public policy or that the church/state issue is irrelevant. As we have often argued, parents have a right to choose religious or other private education for their children. But the nation needs a strong public system supported by all its citizens. At a time when many public schools are struggling to reinvigorate themselves, and when the poor have less choice about schooling, it seems heartless, not to mention demoralizing, to provide tax subsidies for private education. It is therefore to be hoped that state legislatures will hold the line.

President Reagan contends that his tuition tax credit proposal would spur healthy competition and prod public schools to do better. More likely, it would simply add to the nation's ballooning budget deficits - and leave public education worse off than ever. Is this the direction the country wants to go in?