[Jonathan Zimmerman, who teaches history and education at New York University, is the author of Innocents Abroad: American Teachers in the American Century, to be published this fall by Harvard University Press.]

LIKE MOST of my friends and colleagues, I'm outraged by President Bush's assault on basic civil liberties in the so-called War on Terror. We invoke Thomas Jefferson on the rights of man, James Madison on checks and balances, and, most of all, Benjamin Franklin on the dangers of compromising these values: "Those who would give up an essential liberty for temporary security deserve neither liberty nor security."

But here are two words that you'll never hear us say: Abraham Lincoln.

That's because Lincoln's wartime decisions raise the really tough issue that most Democrats continue to evade: When should we give up some liberties in the name of security? And unless we can frame an answer, we don't deserve to win Congress in November or the White House in 2008.

Consider Lincoln's predicament in April 1861, at the outset of the Civil War. Eleven slaveholding states had seceded; four "border states" -- Maryland, Kentucky, Missouri, and Delaware -- remained in the Union but all still practiced slavery.

To win the war, Lincoln had to make sure that these states did not also secede. Together, they would have added 45 percent to the white population of the Confederate States of America. Even more important, they would have nearly doubled the Confederacy's capacity to make guns, ammunition, and the other tools of war.

The most critical state was Maryland, of course, because it bounded the District of Columbia on three sides. On the fourth side lay Virginia, which had already left the Union. If Maryland seceded too, Lincoln would find his national capital surrounded by the enemy.

And he couldn't have that. There were clear pockets of secessionist sentiment in Maryland's biggest city, Baltimore, where many houses flew Confederate flags after the war began. So rather than risk losing the city -- and, quite possibly, the war -- Lincoln sent Army officials into Baltimore to arrest alleged secessionists and jail them at Fort McHenry. (The prisoners included a grandson of Francis Scott Key, who had written "The Star Spangled Banner" while the fort was under British fire, in 1814.)

A few months later, as the Maryland legislature was preparing to vote on secession, Lincoln had 31 of the lawmakers imprisoned on suspicion of Confederate sympathies. They stayed in jail until the next state election, to ensure that pro-Union candidates won.

No charges. No evidence. No trial.

Sound familiar?

Then, as now, the president's enemies mounted constitutional challenges to his actions. One of the people imprisoned in Baltimore, John Merryman, sued for his freedom in federal circuit court. The senior judge was none other than Chief Justice Roger Taney, a Marylander and author of the infamous Dred Scott decision. Taney ruled that Lincoln had no right to jail Merryman without cause, because the Constitution gave Congress -- not the president -- exclusive power to suspend basic liberties in times of war.

Lincoln's response? Go to hell. His primary job, he said, was to win the war, and he needed every possible weapon to do so. He refused to obey Taney's opinion, which would have freed hundreds of Confederate partisans. Who knows what they would have done if they'd been let loose?

That should sound familiar, too. Indeed, almost everything President Bush has done in the "War on Terror" echoes Lincoln's actions during the War Between the States. In the name of national security, the Bush administration has jailed suspected terrorists without showing cause. It has denied them the right to counsel and other basic liberties. It has conducted warrantless eavesdrops on phone calls and e-mails. And it has insisted that the White House -- not Congress -- has the right to do all of this, on its own.

As in the Civil War, meanwhile, the Supreme Court has sought to rein in the president. Most recently, it ruled that the White House could not establish secret military commissions without congressional authority. It's still not clear how the president -- or Congress -- will respond.

But here's what is clear: Benjamin Franklin was wrong. And Abraham Lincoln was right.

There are times when dangers are so immediate -- and so terrifying -- that we do need to sacrifice some freedoms to stop them. And the Civil War was one of those times.

Is the "War on Terror" another? Not yet. Whatever the threat of Islamic terrorism, it doesn't come close to the peril that the Confederates posed to the Union in 1861. Until President Bush can explain exactly why we need his extra-legal measures, we should all stand in opposition to them.

At the same time, though, liberals like myself need to start thinking -- and talking -- about when we, too, would give up some liberties to save the Union. A rash of suicide bombers striking several American cities at the same time? A "dirty bomb" or nuclear attack? A smallpox or anthrax attack?

You might reply that our liberties define our nation: If we abandon them, we give up on America itself. But Abraham Lincoln said otherwise, and lucky for us. By sacrificing a bit of freedom for suspected Confederate sympathizers, he helped win freedom for nearly 4 million enslaved African-Americans.

I think it was worth it. And I bet you do, too.

Until we Democrats can specify when and how we'd take the same harsh measures that Lincoln did, we don't deserve to sit under his mantle. Or to run the country.