WASHINGTON -- The U.S. Supreme Court bolstered the Secret Service's legal immunity Tuesday, throwing out a lawsuit against agents accused of improperly shielding President George W. Bush from protesters a decade ago.

In one of several cases considered Tuesday, the justices unanimously ruled that agents didn't have to defend against claims that they unconstitutionally violated free-speech rights by moving anti-Bush demonstrators farther from the president than Bush supporters.

The case "is scarcely one in which the agents acted without a valid security reason," Justice Ruth Bader Ginsburg wrote for the court.

Seven Bush critics said the Secret Service showed favoritism toward the former president's supporters during his October 2004 campaign stop in Jacksonville, Ore. They said that, unlike pro-Bush demonstrators, they were forced to move two blocks from the hotel where the president was dining.

Before the anti-Bush protesters were moved, they were near an alley next to an outdoor patio that the president had made a last-minute decision to visit.

"When the president reached the patio to dine, the protesters but not the supporters were within weapons range of his location," Ginsburg wrote.

President Barack Obama's administration said Secret Service agents can't be sued as long as they have a valid security reason for their actions. The administration said agents shouldn't have to worry about ensuring that groups with different viewpoints have comparable proximity to the president.

Ginsburg said favoritism by the Secret Service might be unconstitutional if there were "no objectively reasonable security rationale."

The lawsuit, pressed by the American Civil Liberties Union, says the Oregon incident was one of 13 in which the Secret Service kept protesters away from Bush.

The decision reaffirmed that the Secret Service can't "shield the president from criticism," said Steven Shapiro, the ACLU's legal director. "The jury should have been allowed to decide whether this case was actually about security or censorship."

The case is Wood v. Moss, 13-115.

The court also ruled Tuesday that Michigan can't block the opening of an off-reservation American Indian casino because the state's legal challenge is barred by tribal sovereign immunity.

In a 5-4 decision, the high court said the state could not shutter the Bay Mills Indian Community's casino about 90 miles south of its Upper Peninsula reservation.

Indian tribes increasingly have looked to casinos as a source of revenue and have relied on immunity to shield them from government interference. Michigan and more than a dozen other states worry the decision will interfere with their ability to crack down on unauthorized tribal casinos.

Michigan argued that the Bay Mills tribe opened the casino in 2010 without permission from the U.S. government and in violation of a state compact.

Writing for the majority, Justice Elena Kagan said the federal Indian Gaming Regulatory Act allows a state to bring lawsuits challenging casinos operating only on Indian lands. But the Bay Mills casino was opened outside the tribe's reservation, Kagan said, placing it outside the law's coverage.

Because the casino does not fall under federal gaming laws, Kagan said it is subject to the ordinary tribal immunity that extends to off-reservation commercial activities. Kagan said it doesn't matter that the casino was authorized, licensed and operated from the tribe's reservation.

Kagan noted that Michigan officials have other options for dealing with the casino, such as bringing a lawsuit against individual tribal officials or even prosecuting tribal members under criminal laws.

She was joined in her opinion by Chief Justice John Roberts and Justices Anthony Kennedy, Stephen Breyer and Sonia Sotomayor.

In dissent, Justice Clarence Thomas said he disagreed with the Supreme Court's 1998 ruling that extended tribal sovereign immunity to bar lawsuits arising from an Indian tribe's commercial activities outside its territory. In the 16 years since that decision, "tribal commerce has proliferated and the inequities engendered by unwarranted tribal immunity have multiplied," Thomas wrote.

Thomas was joined in dissent by Justices Antonin Scalia, Samuel Alito and Ginsburg.

Scalia also wrote a separate dissent to say he had agreed with the court's 1998 decision, but is now convinced that was wrongly decided. Scalia said he would overrule that case "rather than insist that Congress clean up a mess that I helped make."

The case is Michigan v. Bay Mills Indian Community, 12-515.

In a case that could affect how taxes are collected in other states, the court agreed Tuesday to consider a dispute over how Maryland may tax the income that its residents earn elsewhere.

Maryland law allows residents to deduct income taxes paid to other states from their Maryland state tax. But it does not apply that deduction when it comes to a local "piggyback tax" the state collects for counties and some city governments.

Last year, the Maryland Court of Appeals said the tax violates the Constitution's Commerce Clause. The court said the law discourages Maryland residents from earning money outside the state.

Maryland Attorney General Douglas Gansler said the state has authority to tax all income of its residents, even income earned outside the state. The Obama administration has sided with Maryland, arguing that states have long had the authority to tax the entire income of residents.

While states may choose to grant tax credits to residents for taxes paid in other states, the administration asserts that nothing in the Commerce Clause requires a state to offer those credits or otherwise defer to another state when it comes to taxing its residents.

The case is Maryland State Comptroller of the Treasury v. Wynne, 13-485.

Meanwhile, the court turned away an effort to force a Fox News reporter to reveal her confidential sources for a story about the man charged with killing 12 people in a Colorado movie theater.

The justices did not comment in leaving in place a decision by New York's top appellate court that shielded reporter Jana Winter from being called to testify in a Colorado court. Winter lives and works in New York.

Attorneys for defendant James Holmes wanted Winter to identify the law enforcement officers who gave her information in violation of a judge's gag order. They argued that whoever spoke to Winter might have lied under oath when they denied being her sources, undermining their credibility as potential trial witnesses.

New York's reporter shield law protects reporters from having to identify their sources. Free-press advocates say such protections are vital to encourage whistle-blowers and others to come forward with important information without fear of retribution.

Winter had said she would not reveal her sources, even though she faced a possible jail sentence for refusing.

Information for this article was contributed by Greg Stohr of Bloomberg News and by Sam Hananel, John Flesher, Dan Elliott and Mark Sherman of The Associated Press.

A Section on 05/28/2014