Americans will hear more of this ahead of the election. They also will hear Mr. Bush say that he finally has the power to bring to justice a handful of men behind the 9/11 attacks. The truth is that Mr. Bush could have done that long ago, but chose to detain them illegally at hidden C.I.A. camps to extract information. He sent them to Guantánamo only to stampede Congress into passing the new law.

The 60 or so men at Guantánamo who are now facing tribunals  out of about 450 inmates  also could have been tried years ago if Mr. Bush had not rebuffed efforts by Congress to create suitable courts. He imposed a system of kangaroo courts that was more about expanding his power than about combating terrorism.

While the Republicans pretend that this bill will make America safer, let’s be clear about its real dangers. It sets up a separate system of justice for any foreigner whom Mr. Bush chooses to designate as an “illegal enemy combatant.” It raises insurmountable obstacles for prisoners to challenge their detentions. It does not require the government to release prisoners who are not being charged, or a prisoner who is exonerated by the tribunals.

The law does not apply to American citizens, but it does apply to other legal United States residents. And it chips away at the foundations of the judicial system in ways that all Americans should find threatening. It further damages the nation’s reputation and, by repudiating key protections of the Geneva Conventions, it needlessly increases the danger to any American soldier captured in battle.

In the short run, voters should see through the fog created by the Republican campaign machine. It will be up to the courts to repair the harm this law has done to the Constitution.