President Obama's use of drones to kill U.S. citizens fighting alongside terrorists is not easily sorted. It puts two constitutional absolutes into conflict -- the guarantee of due process to every American, and the obligation to provide for the common defense.

Sometimes it helps to clarify an issue by viewing it in a different historical context, such as this imagined conversation between President Lincoln and Secretary of War Edwin Stanton the day after the Battle of Cold Harbor in June 1864:

Lincoln: Stanton, have you seen these casualty reports?

Stanton: Yes, Mr. President, they are horrible. So many dead boys in blue.

Lincoln: My God, Stanton, we lost 7,000 men in 15 minutes. And for what? Grant is no closer to Richmond than he was before.

Stanton: Liberty requires patience, Mr. President.

Lincoln: Patience? The people have no patience left. They're going to throw us out of office in November if we don't do something right now to bring these damn rebels to heel.

Stanton: Well, Mr. President, we do have the drone. We could send it over Richmond, assassinate Jeff Davis, then, if we can catch Lee somewhere out in the open ...

Lincoln: Come on, Stanton, does that infernal thing actually work?

Stanton: Oh it works. That stuff about Stonewall Jackson's own men shooting him? Cover story we put out so the rebels wouldn't catch on. Took out ol' Stonewall with one missile. Killed some civilians hiding nearby, too, but you know what Sherman says about war being hell.

Lincoln: Oooh, wish you hadn't told me that. They call me "Honest Abe," you know. When can we make this happen?

Stanton: Wait, there's something else. Davis and Lee are still American citizens. Remember, we don't recognize the Confederacy, so we would be killing them without due process.

Lincoln: Give it a rest, Stanton. We suspended habeas corpus and threw all those Copperhead newspaper editors in jail. They were U.S. citizens, too, weren't they?

Stanton: Yes ... but depriving an American of his liberty for a couple of years is one thing. Eventually, he'll be released and go home. Popping a Hellfire missile on his head and killing him, that's for keeps.

Lincoln: And your point is?

Stanton: Wouldn't be anything left of Davis or Lee for us to hang from that sour apple tree! Ha-ha, ha-ha, ha-ha!!!

Lincoln: OMG. Is that what passes for humor among you and your radical friends, Stanton? Sheesh.

Stanton: Just trying to introduce a little levity here, Mr. President.

Lincoln: So after the drone turns Davis and Lee into ashes, the rebels will realize they're doomed and the war will be over. The people will love us and vote us back into office. Sounds like a win-win to me, Stanton.

Stanton: Unfortunately, not quite. Richmond is swarming with ambitious politicians and eager generals. They still have armies in the field and spies and assassins here among us.

Lincoln: So your wonder weapon really isn't the answer. [Frowns, sighs heavily, rests chin in hand, elbow on knee.] Guess we'll just have to take our chances in November.

Stanton: There is one other option. The nuke. Drop that on Richmond and boom, they're all gone, in a flash. End of rebellion. Union saved. No more Cold Harbors. You belong to the ages.

Lincoln: Just like that, in a flash, gone? But wait, they're all citizens, too, aren't they? Where do we draw the line?

Stanton: A small flash that kills one rebel or a big one that kills a host of them? If you want to avoid any more Cold Harbors, what line is there to draw, Mr. President?

Lincoln: Prudence, Stanton, prudence.

Mark Tapscott is executive editor of The Washington Examiner.