Chief Justice William H. Rehnquist is fond of quoting a maxim of Cicero’s: Inter arma silent leges ("In time of war, the laws are silent"). At least, he said in a speech two years ago, "they speak with a muted voice."

Rehnquist and his colleagues are likely to face the first test of their own wartime mettle during the term that began on October 7. A federal appeals court in Philadelphia teed up one issue for review by upholding Attorney General John D. Ashcroft’s claim of power to cloak in secrecy the detentions and deportation trials of noncitizens who he suspects might conceivably have some link to terrorists. That October 8 ruling conflicts with an August 26 decision by a federal appeals court in Detroit holding that the First Amendment requires (with some exceptions) open deportation trials and rebuffing the administration for "placing its actions beyond public scrutiny."

Other post-9/11 civil-liberties issues are percolating through the lower courts. The most momentous is to be argued on October 24 before yet another federal appeals court, in Richmond, Va. At issue is the administration’s unprecedented claim of power to incarcerate indefinitely anyone whom the Pentagon labels an "enemy combatant"-even if he is a U.S. citizen, and even if arrested in this country-with no proof, no criminal charges, no constitutional rights, no family visits, no access to lawyers, no opportunity to protest his innocence, and no hearing before any judge, ever.

Will the Court rubber-stamp even the administration’s most stunning power grabs, its most gratuitous infringements of freedom, its most far-fetched arguments for secrecy-thus inviting even bolder encroachments? Will it go along with policies that are so indifferent to the liberty side of the liberty-security balance as to provoke private expressions of dismay from prominent conservative Republicans, including some who served in the first Bush administration and some who serve in this one?

Or will the justices take their stand with James Madison, who wrote in Federalist 47: "The accumulation of all powers legislative, executive and judiciary in the same hands … may justly be pronounced the very definition of tyranny." And with Justice Robert H. Jackson, who declared in his classic concurrence in Youngstown Sheet & Tube Co. v. Sawyer, the 1952 decision striking down President Truman’s wartime seizure of the steel mills: "No penance would ever expiate the sin against free government of holding that a president can escape control of executive powers by law through assuming his military role." And with the six justices who in 1971 (in New York Times Co. v. United States) spurned President Nixon’s wartime invocation of national security as a basis for censoring publication of the Pentagon Papers. And with Nixon-appointed Justice Lewis F. Powell Jr., author of the 1972 majority opinion (in United States v. United States District Court) rejecting Nixon’s claim of unilateral power to order warrantless wiretaps of domestic radicals. Powell stressed "the tendency of government-however benevolent and benign its motives-to view with suspicion those who most fervently dispute its policies."

The nine current justices are surely aware of the need-made manifest by 9/11-for judicious expansion of the government’s investigative and detention powers. And the encroachments on civil liberties that we have seen over the past 13 months have been relatively mild by comparison with those during the Civil War and the two world wars.

What is nonetheless alarming-and cries out for judicial correction-is this administration’s claim of unilateral power to incarcerate people without exposing its evidence (if any) either to judicial review or to public accountability, while denying some detainees any access to lawyers, and listening in on the attorney-client conversations of others. Given the inexcusable passivity of Congress, these executive power grabs will only become more egregious unless the courts set limits. That is why the secret-trials and military-detention issues now headed for the Supreme Court are so important.

If the justices end up allowing indefinite military incarceration, without due process, of U.S. citizens arrested in this country, it would amount to a blank check for oppression comparable only to the now-infamous 1944 decision in Toyosaburo Korematsu v. United States, which upheld the herding of 110,000 Japanese-Americans into prison camps. That shameful precedent is about the only legal leg the government has to stand on.

The secret immigration trials are more debatable as a legal matter. The justices have not previously extended to such administrative proceedings their line of precedents recognizing a First Amendment right of the public and media to attend criminal trials and pretrial hearings. They should: Deportation trials use similar procedures and are similarly severe in their impact. And the otherwise unchecked power of the executive branch over aliens makes all the more relevant to deportation trials the Supreme Court’s 1936 assertion that "informed public opinion is the most potent of all restraints upon misgovernment."

As a matter of policy and logic, Ashcroft’s argument for blanket secrecy is an insult to the intelligence of the judiciary. He claims that open deportation proceedings might help terrorists by tipping them off to which of their cohorts are behind bars and by airing seemingly innocuous bits of information that could collectively reveal such matters as the government’s "patterns and methods of investigation."

This is, of course, theoretically possible-but no more plausible than the notion that national security might be compromised by bits of information gleaned from, say, the succession of press conferences in which Ashcroft has announced the arrests of suspected terrorists and detailed his department’s investigative coups. Indeed, it might be a net gain for national security (not to mention accountability) if the Supreme Court would order Ashcroft to end both his secret-trial policy and his tedious succession of self-glorifying media briefings.

Given the vast stream of public information that courses constantly through any open society-including the tons of data about the war on terrorism churned out by the administration itself-it’s hard to imagine terrorist groups being in the dark about which of their members are locked up ("They never call, they never write"), or learning anything else of importance from deportation trials that is not available from other channels. And there is no reason to suppose that the Justice Department could not persuade its own immigration judges to close trials (or portions of trials) whenever it can make a plausible showing of danger to witnesses or other real security risks.

Remember, the government has essentially abandoned any suspicion of terrorist links in the cases of all but 1 or 2 percent of the more than 700 noncitizens whom it rounded up on immigration charges in the wake of 9/11. Many were known to be harmless before their secret trials-which has not stopped Ashcroft from referring to them en masse as "aliens who … pose a national security risk to the United States." The government has since deported most of them to places where they are free to share any information aired at their trials with anyone they choose.

And remember, the evidence at a deportation trial is almost never about suspected links (if any) to terrorism. It typically amounts to little more than showing that the defendant’s visa has expired. If the administration does find real evidence linking an immigration defendant to terrorism, it would presumably move him into the criminal-justice system, where all proceedings are public-or perhaps into a military brig, to be held incommunicado, indefinitely, based solely on the president’s say-so.

Which brings me back to Rehnquist. The conservative chief justice is widely seen as a safe bet to support anything and everything the administration does in the name of national security. And it is hard to imagine him striking down secret immigration trials. But even Rehnquist-who is notably solicitous of his own Court’s power-might balk at the Bush regime of military detention without meaningful judicial review.

This is the same Rehnquist who was a Robert Jackson law clerk at the time of the steel seizure case. It "unfolded before my very eyes," he has recalled, with the Truman administration invoking the Korean War to advance a claim of presidential power so broad that it "shocked almost every observer of the Washington scene."

And this is the same Rehnquist who, in a 1984 speech, asserted: "One of the proud and just boasts of the constitutional system of government which we have in the United States is that even the president is not above the law. The justness of the boast is rooted in decisions such as the steel seizure case, in which the Court rebuffed the claims of President Truman, and in the Nixon tapes case, in which the Court rebuffed the claims of President Nixon."

It’s time for another rebuff.