Suppose the FBI receives an anonymous tip that an apartment in Trenton, N.J., was used by Middle Eastern terrorists to prepare the anthrax-laced letters that have convulsed the nation. Could it get a search warrant? Possibly not: Under current case law, an anonymous tip falls short of the "probable cause" necessary to justify searching an apartment.

Now suppose that the FBI arrests a man who has just dropped an anthrax letter into a mailbox. What should the agents do next? Current case law says: Read him his Miranda rights, and if he asks for a lawyer, ask him no questions.

These examples underscore the inadequacy of some of our legal rules to cope with the most dire internal security crisis since the founding of our nation. Even during the Civil War, neither side tried to slaughter civilians. Today, foreign infiltrators are murdering as many Americans as they can. And we are armed with legal rules designed for drug dealers.

In this context, the Bush Administration’s anti-terrorism bill, as modified in Congress, seems modest, incremental, and neither very reassuring nor as alarming as critics suggest. Yes, some provisions are broader than necessary to fight terrorism. But they don’t begin to warrant the stock civil libertarian platitude: "If we sacrifice our liberties, then the terrorists will truly have won."

This is not to suggest that security requires sacrificing very many of our liberties. But we do need to re-evaluate some of the balances that we have struck in the past in devising criminal justice rules for drug dealers, bank robbers, burglars, white-collar criminals, and the usual run of killers. The monsters stalking us now are far, far more dangerous. That’s why some lawyers, both inside and outside government, are quietly exploring some possible innovations more far-reaching than anything that the Administration has publicly proposed. Among the options:

Hold military trials for captured enemies. It is widely assumed that if Osama bin Laden comes out of a cave with his hands up, U.S. or allied forces will kill him on the spot-perhaps after some interrogation without benefit of Miranda warnings. At least on the Afghan front, this is war, not a legal proceeding. And this enemy will be dangerous until dead.

But what should be done with any bin Laden foot soldiers we catch (or have already caught) on the home front? We might well end up with dozens, or even hundreds, of them in custody in the coming years-hopefully before most have succeeded in killing anyone. We can’t just kill them on the spot. But holding ordinary criminal trials could further endanger American lives, because the media spotlight might well inspire attacks by other terrorists demanding the defendants’ release. And the legal rules, by forcing disclosure of critical intelligence secrets, would make it harder to stop future attacks. (See this issue, p. 3350.) Moreover, if we give such people the benefit of the rules restricting the use of even highly relevant evidence, it may be impossible to prove many of them guilty beyond a reasonable doubt. Must we turn such suspects loose, no matter how strong the suspicion that they are bent on mass murder?

Not necessarily, officials say. The Administration is quietly considering another option: trying some accused foreign terrorists as war criminals, before special military tribunals. The President’s constitutional authority to order such trials, with or without explicit congressional approval, is fairly clear. In a 1942 decision, the Supreme Court approved swift, secret military trials of eight German saboteurs armed with explosives who had been secretly landed by U-boats. The Justices reasoned that an enemy "who without uniform comes secretly through the lines for the purpose of waging war by destruction of life or property" was an "unlawful combatant," subject to military trial and not "entitled to the status of prisoners of war."

This fits foreign terrorists like a glove. And both of the men who served the first President Bush as Attorney General-Dick Thornburgh and William Barr-say that military trials may be appropriate in some cases. Barr researched and raised the military-trial option after the 1988 Libyan bombing of a Pan Am jetliner over Scotland, but the Scottish authorities objected.

"Our conventional criminal justice system is designed to apply to people within our political community," Barr says now, "but it doesn’t make sense to extend those rights to foreign enemies who are trying to slaughter us. These people are just like the Nazi saboteurs." Other experts vigorously disagree. Perhaps they are right. But the Administration is more likely to make a wise decision if all options are more publicly debated.

Deport foreigners suspected of terrorist designs. What should we do with foreign tourists, or students, or recent immigrants when the available evidence suggests that they are probably harmless-but quite possibly terrorists? Current law allows such people to go anywhere they want as long as their visas are in good order. This seems foolish. But it would be outrageous to subject probably harmless people who have violated no law to prolonged detention.

One way out of this box would be to pass a new law requiring that such foreigners be removed from the United States if the government certifies, and a judge finds, that there are reasonable grounds to suspect them of terrorist designs. The law could give such suspects the right either to seek vindication in court or to avoid any public stigma by leaving voluntarily.

Clarify probable cause. Fourth Amendment case law has long failed to distinguish clearly between a search for a ticking time bomb (or a vial of anthrax) and a search for stolen goods or an ounce of marijuana. The general rule is that the government must have "probable cause"-usually interpreted in the more-probable-than-not sense-to believe that the proposed search will in fact uncover evidence of a crime.

This makes sense in most cases, but not when the purpose of the search is to prevent mass murder. The Justices hinted last year that they might allow such a preventive search for a bomb even if the police lack probable cause. But the law remains unclear. Police and federal agents could use more specific guidance.

Permit some coercive interrogation. An October 23 Wall Street Journal op-ed, by Jay Winik, relates how Philippine intelligence agents learned in 1995, from one Abdul Hakim Murad, of a plot to assassinate Pope John Paul II, blow up 11 U.S. airliners, and simultaneously crash a plane loaded with nerve gas into the CIA building. The defiant Murad divulged these plans only after weeks of savage torture. "One wonders, of course," Winik adds, "what would have happened if Murad had been in American custody?"

The answer is almost certainly that Murad would have exercised his right to remain silent, and the plot would have gone forward. Nobody argues that our government should engage in torture, even in a case like Murad’s. But some law enforcement officials do suggest anonymously that perhaps we should make more-benign exceptions to the Supreme Court’s rulings that now bar essentially all efforts to interrogate any prisoner who refuses to talk. After all, the plain language of the Fifth Amendment does not say that suspects cannot be pressured to talk. And while the Justices have vastly expanded its scope, the Founders apparently intended it only to bar forcing a suspect to give evidence at his own trial.

In some cases, a few hours of interrogation or a dose of sodium pentothal (the so-called "truth serum") might painlessly extract potentially life-saving information from a terrorist. The Fifth Amendment would forbid use of that information in a trial of that terrorist. That’s as it should be. But current case law would also expose officials who use coercive interrogation of any kind to damage lawsuits, dismissal, conceivably even prosecution. Is that as it should be?

Institute new safeguards. Measures such as these would obviously risk abuse and harm to innocent people. We should find better ways to minimize these risks and harms. For example, the government should pay prompt and generous compensation to people erroneously detained for more than a few hours, such as Dr. Al Bader Al-Hazmi, a Saudi medical resident in San Antonio who endured 13 harrowing days in various jails based on unwarranted FBI suspicions. And perhaps we should discourage misuse of any "terrorism exceptions" to the usual search-and-seizure rules by excluding all evidence thus obtained from cases unrelated to terrorism.

Any or all of these ideas may be misguided. But thinking outside the legal box is a necessary part of the search for ways to avert new catastrophes-catastrophes that could make other measures, so drastic that they are now unthinkable, become unstoppable.