A bit over a week ago, President Bush and his men promised to provide the legal, constitutional and moral justifications for the sort of warrantless spying on Americans that has been illegal for nearly 30 years. Instead, we got the familiar mix of political spin, clumsy historical misinformation, contemptuous dismissals of civil liberties concerns, cynical attempts to paint dissents as anti-American and pro-terrorist, and a couple of big, dangerous lies.

The first was that the domestic spying program is carefully aimed only at people who are actively working with Al Qaeda, when actually it has violated the rights of countless innocent Americans. And the second was that the Bush team could have prevented the 9/11 attacks if only they had thought of eavesdropping without a warrant.

Sept. 11 could have been prevented. This is breathtakingly cynical. The nation's guardians did not miss the 9/11 plot because it takes a few hours to get a warrant to eavesdrop on phone calls and e-mail messages. They missed the plot because they were not looking. The same officials who now say 9/11 could have been prevented said at the time that no one could possibly have foreseen the attacks. We keep hoping that Mr. Bush will finally lay down the bloody banner of 9/11, but Karl Rove, who emerged from hiding recently to talk about domestic spying, made it clear that will not happen — because the White House thinks it can make Democrats look as though they do not want to defend America. "President Bush believes if Al Qaeda is calling somebody in America, it is in our national security interest to know who they're calling and why," he told Republican officials. "Some important Democrats clearly disagree."

Mr. Rove knows perfectly well that no Democrat has ever said any such thing — and that nothing prevented American intelligence from listening to a call from Al Qaeda to the United States, or a call from the United States to Al Qaeda, before Sept. 11, 2001, or since. The 1978 Foreign Intelligence Surveillance Act simply required the government to obey the Constitution in doing so. And FISA was amended after 9/11 to make the job much easier.

Only bad guys are spied on. Bush officials have said the surveillance is tightly focused only on contacts between people in this country and Al Qaeda and other terrorist groups. Vice President Dick Cheney claimed it saved thousands of lives by preventing attacks. But reporting in this paper has shown that the National Security Agency swept up vast quantities of e-mail messages and telephone calls and used computer searches to generate thousands of leads. F.B.I. officials said virtually all of these led to dead ends or to innocent Americans. The biggest fish the administration has claimed so far has been a crackpot who wanted to destroy the Brooklyn Bridge with a blowtorch — a case that F.B.I. officials said was not connected to the spying operation anyway.

The spying is legal. The secret program violates the law as currently written. It's that simple. In fact, FISA was enacted in 1978 to avoid just this sort of abuse. It said that the government could not spy on Americans by reading their mail (or now their e-mail) or listening to their telephone conversations without obtaining a warrant from a special court created for this purpose. The court has approved tens of thousands of warrants over the years and rejected a handful.

As amended after 9/11, the law says the government needs probable cause, the constitutional gold standard, to believe the subject of the surveillance works for a foreign power or a terrorist group, or is a lone-wolf terrorist. The attorney general can authorize electronic snooping on his own for 72 hours and seek a warrant later. But that was not good enough for Mr. Bush, who lowered the standard for spying on Americans from "probable cause" to "reasonable belief" and then cast aside the bedrock democratic principle of judicial review.

Just trust us. Mr. Bush made himself the judge of the proper balance between national security and Americans' rights, between the law and presidential power. He wants Americans to accept, on faith, that he is doing it right. But even if the United States had a government based on the good character of elected officials rather than law, Mr. Bush would not have earned that kind of trust. The domestic spying program is part of a well-established pattern: when Mr. Bush doesn't like the rules, he just changes them, as he has done for the detention and treatment of prisoners and has threatened to do in other areas, like the confirmation of his judicial nominees. He has consistently shown a lack of regard for privacy, civil liberties and judicial due process in claiming his sweeping powers. The founders of our country created the system of checks and balances to avert just this sort of imperial arrogance.

The rules needed to be changed. In 2002, a Republican senator — Mike DeWine of Ohio — introduced a bill that would have done just that, by lowering the standard for issuing a warrant from probable cause to "reasonable suspicion" for a "non-United States person." But the Justice Department opposed it, saying the change raised "both significant legal and practical issues" and may have been unconstitutional. Now, the president and Attorney General Alberto Gonzales are telling Americans that reasonable suspicion is a perfectly fine standard for spying on Americans as well as non-Americans — and they are the sole judges of what is reasonable.

So why oppose the DeWine bill? Perhaps because Mr. Bush had already secretly lowered the standard of proof — and dispensed with judges and warrants — for Americans and non-Americans alike, and did not want anyone to know.

War changes everything. Mr. Bush says Congress gave him the authority to do anything he wanted when it authorized the invasion of Afghanistan. There is simply nothing in the record to support this ridiculous argument.

The administration also says that the vote was the start of a war against terrorism and that the spying operation is what Mr. Cheney calls a "wartime measure." That just doesn't hold up. The Constitution does suggest expanded presidential powers in a time of war. But the men who wrote it had in mind wars with a beginning and an end. The war Mr. Bush and Mr. Cheney keep trying to sell to Americans goes on forever and excuses everything.

Other presidents did it. Mr. Gonzales, who had the incredible bad taste to begin his defense of the spying operation by talking of those who plunged to their deaths from the flaming twin towers, claimed historic precedent for a president to authorize warrantless surveillance. He mentioned George Washington, Woodrow Wilson and Franklin D. Roosevelt. These precedents have no bearing on the current situation, and Mr. Gonzales's timeline conveniently ended with F.D.R., rather than including Richard Nixon, whose surveillance of antiwar groups and other political opponents inspired FISA in the first place. Like Mr. Nixon, Mr. Bush is waging an unpopular war, and his administration has abused its powers against antiwar groups and even those that are just anti-Republican.

The Senate Judiciary Committee is about to start hearings on the domestic spying. Congress has failed, tragically, on several occasions in the last five years to rein in Mr. Bush and restore the checks and balances that are the genius of American constitutional democracy. It is critical that it not betray the public once again on this score.

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