WASHINGTON - A lone cross built to honor the dead of World War I, bolted to a desert rock on public land, raises a host of complicated issues about which religious displays violate the Constitution's ban on establishment of religion and who may challenge them.

But the Supreme Court yesterday seemed disinclined to answer most of them.

Justices spent nearly half of the oral argument deciding what they were deciding about the 61/2-foot cross in the Mojave National Preserve in California and appeared to settle on a rather narrow question: whether Congress solved the problem by trying to transfer the land on which the cross sits to private ownership.

There was no agreement.

Solicitor General Elena Kagan said lawmakers did the best they could in 2004 to preserve the memorial built by veterans more than 75 years ago and to abide by the decision of the U.S. Court of Appeals that a cross on public land is unconstitutional.

Congress had a choice, Kagan said, to take down the memorial, which meant an enormous amount to veterans, or to dissociate the government from that memorial. "And what Congress did was to completely dissociate the government from that memorial," she said.

Peter Eliasberg, representing the American Civil Liberties Union, said Congress did the opposite: It designated the site a national memorial, putting it in the same category as the Washington Monument and Mount Rushmore. It turned the land over to the Veterans of Foreign Wars, whose members first built the cross in the 1930s, rather than put it up for bid.

The government "has made a significant number of affirmative steps to ensure that the cross remains up," he said, in the face of the lower court's decision that it must come down.

The case was the first major opportunity for the court under Chief Justice John G. Roberts Jr. to delve into the meaning of the First Amendment command that "Congress shall make no law respecting an establishment of religion." Previous court rulings on religious displays have been mostly narrow and case-specific, producing few rules on who may challenge government actions or what violates the Establishment Clause.

Justices seemed uninterested in reviewing the lower court's decision, which found that a former park superintendent who objects to religious displays on public land is entitled to bring the lawsuit.

Only Justice Antonin Scalia seemed to want to decide the more basic question of whether the cross was unconstitutional in the first place. He had a testy exchange with Eliasberg about whether the symbol could also double as a secular marker for the war dead of all faiths. Scalia said the cross was the "common symbol of the resting place of the dead."

Eliasberg drew laughter from the courtroom when he responded: "I have been in Jewish cemeteries. There is never a cross on a tombstone of a Jew."

Justice Ruth Bader Ginsburg drew from Kagan that the Mojave cross was the only one of the fewer than 50 national memorials that consists of a lone religious symbol. Justice John Paul Stevens sharply questioned whether Congress had really disassociated itself from the cross by saying the VFW can do whatever it wishes with the site. "Do you think anyone thought there is the remotest possibility they would put up a different memorial?" he asked Kagan.

Veterans groups and others have worried that a ruling that the cross is unconstitutional would endanger other memorials that employ religious imagery, such as the Argonne Cross at Arlington.

Justices seemed disinclined to answer that. But Eliasberg said those memorials fit into a context that should not be challenged: "In Arlington, there is a cross that is surrounded by a sea of tombstones with symbols of the faith of all of the different service members. I don't think anyone would perceive that the government was favoring one particular religion."