Washington ? Stepping for the first time into the legal fight over the government’s response to Sept. 11, the Supreme Court stopped a federal judge Friday from letting the public and press attend deportation hearings for immigrants detained after the terrorism attacks.

In a one-sentence order, the court granted the Bush administration’s request to block the judge and keep the hearings closed while a federal appeals court in Philadelphia reviews the issue.

The court did not explain its decision to step into the legal dispute, which erupted after news organizations challenged a government policy issued 10 days after the attacks. The policy required immigration judges to close the hearings in so-called “special interest” cases that involved detainees suspected of having information about terrorism.

The government has relied on the policy to stage secret hearings for more than 700 detainees arrested after Sept. 11. Most have since been released or deported. About 75 people remain in detention, according to a lawyer involved in the case.

The dispute, pitting the government’s interest in fighting terrorism against the concern for protecting civil liberties, is the first of its kind to reach the court after the Sept. 11 attacks. Other highly sensitive disputes that also appear headed to the court in coming months include the government’s practice of designating immigrants as “material witnesses” and the detention of American citizens in military custody without placing charges against them.

“There’s no question that the Supreme Court is going to sooner rather than later be faced with how we should balance security and civil liberties in a post-Sept. 11 era,” said David Cole, a professor at Georgetown University Law Center who is challenging the government policy that closed the immigration hearings to the public.

Although the court did not address the merits of the policy, observers said its order indicates it viewed the matter seriously and recognized the harm in opening the hearings to the public before the appeals court had considered the matter.

“They’re taking a cautious and sensible approach to give themselves and other courts an opportunity to consider these questions in a judicious manner,” said Erik Jaffe, a Washington, D.C., lawyer who closely follows the court.

The order came the same day the court announced it would consider next fall another immigration case that examines the treatment of foreign nationals. That case asks whether the government can hold without bond foreign nationals who commit crimes to make sure they don’t flee before deportation proceedings.

At issue is whether a 1996 federal law authorizing their detention without a bond hearing violates the Constitution’s Due Process Clause.

The court’s order Friday in the post-Sept. 11 immigration case effectively stays a decision of U.S. District Judge John W. Bissell, who ruled last month that the government’s blanket policy to close even the most routine hearings violated the First Amendment.

The New Jersey judge said the government must show that an open proceeding could result in the disclosure of sensitive information.

The administration appealed Bissell’s decision to a federal appeals court in Philadelphia, which agreed to consider the matter on an expedited basis, but refused to block the judge’s order in the meantime.

The Justice Department, citing pressing national security concerns “of the highest order,” then urged the high court to step in and keep the hearings closed. In court papers, it stressed the government’s “overpowering and urgent need to safeguard its ongoing terrorism investigations and the vital necessity to protect this nation.”

It argued that Bissell had created an “unprecedented First Amendment right” to allow the public and press into deportation proceedings.

“If these proceedings are opened to the public during the critical phase of the current urgent threat to national security, terrorist organizations will have direct access to information about the government’s ongoing investigation,” the administration said.

Disclosure could cause “irreparable harm to public safety, national security and critically important ongoing criminal investigations,” it argued. Allowing the public into the hearings could give terrorists insight into government investigations and tip them off to evidence that judges and the press may not discern.

“The harms that would result from this disclosure can never be undone,” the Justice Department said.

The Justice Department was “obviously pleased” by the Supreme Court’s decision to step in and block Bissell’s decision, a spokeswoman said Friday.

Tom Goldstein, a Washington, D.C., lawyer and Supreme Court watcher, said the court’s action was a “highly unusual step” and indicated the court was “favorably inclined” toward the government’s position.

“It will be interpreted by the lower courts as a signal to take the government’s interests very seriously,” Goldstein said.

But Cole cautioned against reading too much into the court’s order. Pointing to government arguments about the irreparable harm to national security, Cole said the court could have wanted the appeals court to fully think through the issue “before the cat is let out of the bag.”

Cole said he still was optimistic the hearings could be opened to the public and press. He noted that two federal courts had declared the government policy unconstitutional, and two federal appellate courts had declined to block those decisions.

Cole said the government had applied the policy to more than 700 detainees, and that 73 still were being held. None has been charged in connection with the investigation of the Sept. 11 attacks, he said.

Keeping the proceedings secret, he said, “makes that kind of dragnet possible.”

“It denies public scrutiny that would call into question many of the actions that the government took with respect to these people,” Cole said.

Nancy Chang, senior litigation attorney at the Center for Constitutional Rights, which also is challenging the policy, said the press and the public “play a crucial role in keeping the immigration process honest.”

“Their participation and attendance in hearings is critical to the democratic process,” she said.