For more than five years, President Bush authorized government spying on phone calls and e-mail to and from the United States without warrants. He rejected offers from Congress to update the electronic eavesdropping law, and stonewalled every attempt to investigate his spying program.

Suddenly, Mr. Bush is in a hurry. He has submitted a bill that would enact enormous, and enormously dangerous, changes to the 1978 law on eavesdropping. It would undermine the fundamental constitutional principle — over which there can be no negotiation or compromise — that the government must seek an individual warrant before spying on an American or someone living here legally.

To heighten the false urgency, the Bush administration will present this issue, as it has before, as a choice between catching terrorists before they act or blinding the intelligence agencies. But the administration has never offered evidence that the 1978 law, the Foreign Intelligence Surveillance Act, hampered intelligence gathering after the 9/11 attacks. Mr. Bush simply said the law did not apply to him.

The director of national intelligence, Michael McConnell, said yesterday that the evidence of what is wrong with FISA was too secret to share with all Americans. That’s an all-too-familiar dodge. Senator Dianne Feinstein, Democrat of California, who is familiar with the president’s spying program, has said that it could have been conducted legally. She even offered some sensible changes for FISA, but the administration and the Republican majority in the last Congress buried her bill.

Mr. Bush’s motivations for submitting this bill now seem obvious. The courts have rejected his claim that 9/11 gave him virtually unchecked powers, and he faces a Democratic majority in Congress that is willing to exercise its oversight responsibilities. That, presumably, is why his bill grants immunity to telecommunications companies that cooperated in five years of illegal eavesdropping. It also strips the power to hear claims against the spying program from all courts except the Foreign Intelligence Surveillance Court, which meets in secret.

According to the administration, the bill contains “long overdue” FISA modifications to account for changes in technology. The only example it offered was that an e-mail sent from one foreign country to another that happened to go through a computer in the United States might otherwise be missed. But Senator Feinstein had already included this fix in the bill Mr. Bush rejected.

Moreover, FISA has been updated dozens of times in the last 29 years. In 2000, Lt. Gen. Michael Hayden, who ran the National Security Agency then, said it “does not require amendment to accommodate new communications technologies.” And since 9/11, FISA has had six major amendments.

The measure would not update FISA; it would gut it. It would allow the government to collect vast amounts of data at will from American citizens’ e-mail and phone calls. The Center for National Security Studies said it might even be read to permit video surveillance without a warrant.

This is a dishonest measure, dishonestly presented, and Congress should reject it. Before making any new laws, Congress has to get to the truth about Mr. Bush’s spying program. (When asked at a Senate hearing yesterday if Mr. Bush still claims to have the power to ignore FISA when he thinks it is necessary, Mr. McConnell refused to answer.)

With clear answers — rather than fearmongering and stonewalling — there can finally be a real debate about amending FISA. It’s not clear whether that can happen under this president. Mr. Bush long ago lost all credibility in the area where this law lies: at the fulcrum of the balance between national security and civil liberties.