A New Jersey court decision outlawing a ''minute of silence'' statute on constitutional grounds could help set up a United States Supreme Court test of highly controversial prayer-in-school laws.
Last term, the high court sidestepped the issue in test cases brought to it from Alabama and Pennsylvania. Both involved teacher-led prayer in the classroom.
However, since that time pressures have mounted - particularly from political conservatives backed by the Reagan administration - to allow some type of voluntary school prayer in public schools.
Now 20 states have laws on the books permitting a period of silence in the classroom. Many have been challenged - but with mixed results. Prayer laws of this type have been struck down in Tennessee and New Mexico. A Massachusetts law has withstood a legal test. And earlier this month, a federal district judge in Alabama banned prayer in that state's schools as a result of an appeals-court decision.
Meanwhile, Congress continues to grapple with two proposed constitutional amendments that would sanction different forms of organized classroom prayer. An amendment favored by President Reagan and many fundamentalist religious groups would permit audible prayer in public schools. Another, written by Sen. Orrin G. Hatch (R) of Utah, would allow silent prayer or meditation.
A recent Gallup poll indicates that 81 percent of Americans favor an amendment which would allow voluntary prayer in the schools.
In 1962, the US Supreme Court ruled that organized prayer in the public schools violates parts of the First Amendment to the US Constitution that prohibits state-established religion.
The New Jersey decision by federal district Judge Dickinson R. Debevoise appears to follow the high court's legal rationale of more than 20 years ago.
In striking down the state legislation mandating a ''minute of silence'' for ''quiet and private contemplation or introspection,'' Judge Debevoise said the measure had a definite ''religious'' purpose and violated the Constitution's religious-liberty protections.
Specifically, he pointed out in a detailed 41-page decision that a state-mandated moment of silence:
* Advances the religion of some while inhibiting the religion of others.
* May be offensive to those whose beliefs call for prayers that require ''movement and sound.''
* Conflicts with the beliefs of those who profess no religion and to whom any form of prayer is offensive.
''A required minute of silence would put children and parents who believe in prayer in the public schools against children and parents who do not,'' Judge Debevoise wrote in his decision.
The New Jersey judge saw no conflict between his findings and that of a US Supreme Court ruling last year (Mueller v. Allen) that upheld a Minnesota statute allowing tuition tax credits to parents of children who attend both private and public schools. Here, the high court decided that state legislation allowing this type of financial aid was not in conflict with their own guidelines regarding the separation of church and state.
Proponents of public aid for private schools hailed the Minnesota decision as significant in breaking down the ''wall'' of separation between church and state - which they said was intended by the Founding Fathers to be a ''porous'' one, not solid one.
However, Judge Debevoise termed the Mueller case of ''very limited utility in the present case.'' He called it ''the most recent of a long line of cases dealing with the question of the extent to which state legislation may, directly or indirectly, aid sectarian schools.
''The facts of those cases and the problems of church-and-state relations which they raise are quite different from the facts and problems raised by the school prayer cases,'' he wrote.
The New Jersey controversy has attracted national attention. The statute was enacted into law in December, when state lawmakers overrode a veto by the governor. Since then it has stirred debate in many communities.
In Princeton, for instance, some students who considered the measure ''enforced prayer'' threatened to disrupt classrooms. In other districts, parents who felt the exercise violated their religious beliefs had to decide whether to have their children excuse themselves during the moment of silence.
Proponents of the silence measure argued in court that it had a secular rather than a religious purpose. They also said that it provided students with a good transition between nonschool activities and classroom curricula. Judge Debevoise saw this as ''evidence of the religious intent of the enactment.''
If the Supreme Court does decide to finally look at moment of silence laws, the New Jersey case is almost certain to be prominently considered. It is not now on the high court's docket for this term. But some legal scholars say it may be added.