ASHINGTON, May 19 — Barely a year after ruling that the Constitution does not ban the use of taxpayer money for religious school tuition, the Supreme Court today agreed to take the next step and decide whether a public subsidy for religious instruction may under some circumstances be constitutionally required.

This potentially explosive issue reached the court in an appeal by the State of Washington, which like many other states has a provision in its Constitution that prohibits the use of public money for religious instruction. The state turned down an application for a scholarship from an otherwise eligible student who sought a theology degree at a private Christian college.

The student sued and won a ruling from the federal appeals court in San Francisco that the state policy amounted to unconstitutional discrimination against religion.

As supporters of tuition vouchers were quick to point out, the case opens the next front in their long-running effort to establish what they describe as a neutral playing field on which explicitly religious activities can stake a constitutional claim to public support on the same basis as secular activities. State constitutions have stood as an obstacle to that goal.

Thirty-seven state constitutions contain a proscription against public financial support for religion. These provisions are generally referred to as Blaine amendments, after the sponsor of a failed effort to attach such an amendment to the federal Constitution in 1875.

They have come under increasing scrutiny in light of recent Supreme Court decisions that have invoked a general principle of equal access to expand the space for religion in public life.

There is no religion case on the court's docket for the current term, which will end in about six weeks. This new case, Locke v. Davey, No. 02-1315, will be argued next fall, and could mark the court's next term as an extremely important one for religion even without the prospect of the Pledge of Allegiance case that the Bush administration has recently appealed to the court. That is the case in which the United States Court of Appeals for the Ninth Circuit — the same court that ruled in the Washington State case — found a violation of the separation of church and state in the phrase "under God." The Supreme Court has not yet said whether it will hear the case.

Washington makes state scholarships available for use at accredited religious colleges, as long as the money is not used to pursue a degree in theology. The policy, embodied in a state law as well as the Washington Constitution, was challenged in 1999 by Joshua Davey, a student at Northwest College, in Kirkland, near Seattle, where he was seeking a degree in pastoral ministries.

Mr. Davey, represented by the American Center for Law and Justice, a law firm affiliated with the Rev. Pat Robertson, lost in Federal District Court in Seattle, which held that while the state could not prevent Mr. Davey from pursuing religious studies, it was under no obligation to finance those studies.

Last July, the Ninth Circuit overturned that decision, ruling 2 to 1 that the state scholarship program had established a "fiscal forum," much as a government might establish a public forum for free speech. Just as religious speech may not be excluded from a public forum, the benefits of a fiscal forum "may not be denied on account of religion," the appeals court said.

In its appeal to the Supreme Court, Washington said the ruling placed the state in an "intolerable situation." Its own State Supreme Court has upheld the limitation, a part of the state's Constitution since Washington's admission to the Union in 1889, while the federal appeals court has in effect declared the provision unconstitutional. The issue was one of national significance, the state said.

The Institute for Justice, a leader in the movement to expand the use of vouchers for religious school tuition, also urged the justices to take the case, but to affirm rather than reverse the Ninth Circuit's decision. The institute, a public policy and litigating organization based here, has filed lawsuits around the country attacking Blaine amendments, which stand as significant obstacles to expansion of the Ohio voucher program that the Supreme Court upheld last June. Clark Neily, a lawyer with the group, said that the case the court accepted today would "resolve all these cases under one unified theme."

There were also these other developments at the court today.

Interrogation

The next term is also emerging as an important one for the law of police interrogation, with the justices today accepting a third case on that subject. In an appeal filed by the State of Missouri, the court agreed to clarify a 1985 decision on the prosecution's use of statements made by a suspect who was initially questioned without receiving the required Miranda warnings and who then waived his Miranda rights and continued to talk.

In the 1985 decision, Oregon v. Elstad, the court held that the initial violation did not taint statements given by suspects who agreed to talk after eventually receiving the advice that they could remain silent and consult a lawyer.

But in that case, the police officers' initial failure to give the warnings had been inadvertent. In the new case, Missouri v. Seibert, No. 02-1371, the police had deliberately deferred giving the warnings to a woman they were questioning after a suspicious fire that had killed a man who was living in her mobile home.

One of the officers later testified that he had received specific training in this technique, in which suspects who have been encouraged to make incriminating statements are likely to keep talking after they receive the warnings. The woman, Patrice Seibert, was convicted of second-degree murder.

The Missouri Supreme Court overturned the conviction in a 4-to-3 decision holding that an intentional Miranda violation tainted the subsequent statements by depriving suspects of the ability to make a knowing and intelligent waiver of their Miranda rights. Missouri told the justices in its appeal that there was considerable confusion about the scope of the 1985 decision.

Punitive Damages

The court vacated two substantial punitive damage awards against the Ford Motor Company. In one case, a California jury awarded $290 million to the family of three people killed when a Ford Bronco rolled over. In the other, the family of a Kentucky man whose Ford pickup truck went into reverse and crushed him won $18 million.

In both the first case, Ford v. Romo, No. 02-1097, and the second, Ford v. Smith, No. 02-1096, the justices ordered the state courts to reconsider the awards in light of a punitive damages case, State Farm v. Campbell, that the Supreme Court decided last month in favor of the defendant. The interest in the cases today lay in the fact that while the State Farm case involved a purely economic injury, the Ford cases were lawsuits alleging that a defective product had caused death.

The State Farm decision last month set stringent limits on punitive damages but left open the prospect that more pro-plaintiff rules might apply to product liability cases involving severe injury and death. The action today was still not the final word, and the Ford cases might well return to the Supreme Court eventually.

Guantánamo Case

Without comment, the court let stand a ruling that a coalition of clergy members, lawyers and law professors lacked standing to sue on behalf of those held in detention at Guantánamo Bay, Cuba. The Ninth Circuit had earlier rejected the case, Coalition of Clergy v. Bush, No. 02-1155.