Welcome to the President's Inbox, a CFR podcast about the foreign policy challenges facing the United States.

I'm Jim Lindzeg, Director of Studies at the Council on Foreign Relations.

This week's topic is The Laws of War.

With me to discuss the laws governing warfare and how they apply to the ongoing war between Israel and Hamas is Matthew Waxman. Matt is an adjunct senior fellow for law and foreign policy here

at the Council on Foreign Relations. He is also the Livu Librescu professor of law at Columbia

Law School, where he directs the National Security Program. Matt has held several positions

in the U.S. government, including Principal Deputy Director of Policy Planning at the State Department,

and executive assistant to the National Security Advisor.

After graduating from Yale Law School, Matt was a law clerk for U.S. Supreme Court Justice,

David Souter.

Matt, thanks for coming back on the president's inbox.

Thanks for having me, Jim.

Now, Matt, it's a term I'm seeing a lot in discussions these days, and that is the term

the laws of war. What actually does that mean? Sure. So I think it makes sense to think about the laws

of war, sometimes called the law of armed conflict or international humanitarian law as two layers. And we lawyers like to

use Latin terms. So the first layer is the use ad bellum, the legality of resort to force, resort to war.

And the second layer is use in bellow or law governing how war is waged, the conduct of war.

And that distinction is important because it forms the basis of this idea that even if a war is just, it still must be conducted justly.

Okay. So actually, tease it out for me because I think those two could. it still must be conducted justly.

Okay, so actually tease it out for me because I think those two concepts get conflated.

So my understanding is that a war can begin unjustly, but the combatants need to abide by certain rules of conduct.

Likewise, you can have a war that begins justly and is fought unjustly. But help me unpack that. First, what determines whether a war is just?

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