WASHINGTON (AP) — The Supreme Court, which asks for God's protection before every public session, will settle a dispute over prayer in the halls of government.

The case being argued at the court Wednesday involves prayers said at the start of town council meetings in Greece, N.Y., a Rochester suburb. It is the court's first legislative prayer case since 1983, when the justices said that an opening prayer is part of the nation's fabric and not a violation of the First Amendment.

But the federal appeals court in New York held that the town crossed a line and violated the Constitution by opening nearly every meeting over an 11-year span with prayers that stressed Christianity.

Under Chief Justice John Roberts, and with the replacement of Justice Sandra Day O'Connor with Justice Samuel Alito in 2006, the court has been more open to religion in public life. The case may serve as a test of the ongoing viability of the decision in the 1983 case, Marsh v. Chambers.

But it also could have an even broader impact, giving conservative justices the opportunity to jettison legal rules that have tended to rein in religious expression in the public square.

That is what some conservative Christian groups, Republican lawmakers and state officials are hoping for, and it's what liberal interest groups fear. The issue extends well beyond prayer and could affect holiday displays, aid to religious schools, Ten Commandments markers and memorial crosses.

The Supreme Court "has issued a series of narrowly divided and splintered decisions that have confused the lower courts, baffled the public and incentivized government officials to suppress legitimate religious expression in order to avoid the costs and hazards of litigation," said 85 members of Congress, almost all Republicans, in a court filing.

Among the examples of confusion cited are the court's twin rulings on a single day in 2005 that upheld a Ten Commandments monument on the grounds of the Texas state capitol in Austin, yet declared unconstitutional a display in the McCreary County courthouse in Kentucky.

The lawmakers are among those calling on the justices to adopt a clear rule — requiring government to refrain from coercing participation in any religion or religious exercise, or from creating a state religion — to determine whether a practice runs afoul of the First Amendment's clause barring laws "respecting an establishment of religion," known as the Establishment Clause.

But doing so would drastically cut back on protections against instances in which governments abandon religious neutrality, including the dispute in the New York town of Greece, said Erwin Chemerinsky, a liberal legal scholar and dean of the University of California at Irvine law school. If the court adopts the test that the lawmakers and others are urging, "very little will be left of the Establishment Clause," Chemerinsky said.

Chemerinsky said the prayers in Greece should be held unconstitutional under any standard.

The Obama administration is taking a middle ground, siding with the town because it said the appeals court made a mistake in departing from the Supreme Court's 30-year-old precedent. "Courts should not parse or evaluate the content of prayer," Solicitor General Donald Verrilli wrote in his brief, relying on the 1983 case. He said the administration has an interest in protecting the tradition of opening each day of Congress with a prayer that stretches back to the nation's founding.

At the Supreme Court, the justices stand at their seats while Marshal Pam Talkin asks God to "save the United States and this honorable court."

The facts of the situation in Greece, a town of roughly 100,000 people, are not in dispute.

From 1999 through 2007, and again from January 2009 through June 2010, every meeting was opened with a Christian-oriented invocation. In 2008, after residents Susan Galloway and Linda Stephens complained, four of 12 meetings were opened by non-Christians, including a Jewish layman, a Wiccan priestess and the chairman of the local Baha'i congregation.

A town employee each month selected clerics or lay people by using a local published guide of churches. The guide did not include non-Christian denominations, however. The appeals court found that religious institutions in the town of just under 100,000 people are primarily Christian, and even Galloway and Stephens testified they knew of no non-Christian places of worship there.

The two residents filed suit and a trial court ruled in the town's favor, finding that the town did not intentionally exclude non-Christians. It also said that the content of the prayer was not an issue because there was no desire to proselytize or demean other faiths.

But a three-judge panel of the 2nd U.S. Circuit Court of Appeals said that even with the high court's 1983 ruling, the practice of having one Christian prayer after another amounted to the town's endorsement of Christianity.

Richard Garnett, a University of Notre Dame law professor and former Supreme Court clerk, said it is likely that the court will reverse the appeals court and that a narrow ruling of the sort sought by the administration could cause some liberal justices to join their conservative colleagues.

But because the case can be resolved narrowly, Garnett said it probably is not one the justices will use to order judges to take a more hands-off approach to instances in which religion and government mix.

The case is Greece v. Galloway, 12-696.