The Laws of War, With Matthew Waxman

LINDSAY:
Welcome to The President's Inbox, a CFR podcast about the foreign policy challenges facing the United States. I'm Jim Lindsay, 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's also the Liviu 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.

WAXMAN:
Thanks for having me, Jim.

LINDSAY:
Now Matt, there'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?

WAXMAN:
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 jus ad bellum, the legality of resort to force, resort to war. And the second layer is jus in bello, 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.

LINDSAY:
Okay, so actually tease it out for me because I think those two concepts get conflated. So my understanding is 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?

WAXMAN:
The main way in which war is justified is self-defense. And some argue that Israel doesn't have a right of self-defense in this case either because Hamas is not a state or because it's actually Palestinian forces that are waging at defensive war to reclaim their rightful territory. I don't think either of those arguments were persuasive even before October 7th. And I think Israel's right to self-defense is the much stronger claim, I would say a decisive claim, after suffering such a barbaric attack and massacre on October 7th.

Hamas killed well over a thousand people, mostly civilians, including children, elderly. It took hostages—all of which are war crimes—in this case carried out with genocidal intent. There is, I think, not a country on earth that would not assert self-defense, and they would be within their rights to do so. Still, Israel has the duty to carry out this war in accordance with the law. The fact that it's a just war does not in any way absolve Israel from its responsibility to follow the rules of warfare.

LINDSAY:
I want to get to this question of, as you called it, jus in bello in a moment, but I still want to stick on this issue of the legality of the ongoing conflict. And it's really the question of what status Hamas has under international law given that it is not a state. I take your point that all states have a legal right under the UN Charter to self-defense, but what is the status of any non-state actor, which is what Hamas is, under international law?

WAXMAN:
So there are a few things that Hamas's status or character as a non-state actor mean for international law. First, although Hamas is not a state that could be a party to treaties like the Geneva Conventions, it is still bound by certain rules of what's called customary international law, based on the practice of states over time. This includes some basic rules of humanity: responsibilities to target only so-called military targets, not to take hostages. Hamas can still commit and, I think, has clearly committed war crimes in this case.

The second reason why its status or character as a non-state actor sometimes gives rise to some controversy about the justice in war is there is a view that under the UN Charter, which you referenced, states have a right of self-defense really only against other states. I don't think that rule really makes any sense given that some terrorist organizations can now wage violence at a level of intensity, scale previously only achievable by organized states. And I think, at least since September 11th when it was pretty uncontested that the United States had a right of self-defense against Al-Qaeda, I think the international law really well recognizes now the idea that a right of self-defense can in fact be waged against a non-state actor like a terrorist organization.

LINDSAY:
I would think, Matt, that any interpretation of international law that suggested that states only had a right of self-defense against other states would create a yawning loophole in international law and create all kinds of mischief. Among other things, it would empower states to support proxies that aren't states to go after their adversaries.

WAXMAN:
Well, that's exactly right. One of the reasons why the right of self-defense is such an important core concept in international law is that any system of law that didn't recognize a right of self-defense would simply crumble, right? There'd be no way in which such a system could be ... could over time still command respect in a world in which states face very severe threats from terrorist organizations. I think recognizing the right of self-defense against major terrorist organization is critical to the vitality of international law in this area.

LINDSAY:
So let's talk about the laws governing how wars are fought. Now, I will note that there are a number of international agreements on this score. What comes to mind for me, obviously the Geneva Conventions, of which there are several, the International Criminal Court. There's the UN Charter. So help me understand what the rules are about how wars are to be conducted.

WAXMAN:
Sure. So the laws of war, the law of armed conflict, sometimes called international humanitarian law, governing the conduct of war at the most general level balances two concepts: military necessity, or the imperative to wage war effectively, and humanitarian values like reducing human suffering. And while the patchwork of international law is complicated, it really boils down to a few key principles. And I would say the two most important here are the principles of distinction and proportionality.

The principle of distinction means that forces may only deliberately strike military targets or personnel. They can't deliberately target civilians or civilian property. Now, this is not a rule that no civilians may be killed incidentally. That's a tragic consequence of every war. And it's a horrible consequence of this war on a very large scale. But it does require that civilians and civilian property not be deliberately targeted. And there's an important corollary to this, which is that the defender must not deliberately put civilians in harm's way. It can't use human shields. It can't store military supplies in mosques or schools or hospitals. And when it does, that civilian site can lose its protection, can lose its immunity from being targeted.

But that brings us to the second key principle, which is proportionality. And the proportionality principle goes like this, that the anticipated civilian harm of a military operation can't be excessive compared to the expected military gain. Now, that's obviously easy to state as a rule. It's hard to apply in practice because neither human suffering or military necessity can easily be quantified. But I think an illustration would be that you couldn't bomb an entire housing complex in order to take out just a single sniper.

LINDSAY:
Okay, there's a lot there, so let's unpack it. I want to begin with the first principle, the principle of distinction, in that you cannot deliberately target civilians. One of the arguments I have seen or read, particularly on Twitter, are people advancing the following argument: Hamas has attacked Israel in a particularly brutal way, Israel is free to attack in any way it so chooses—what I might call the tit-for-tat rule. If you behave badly, all bets are off. How do you assess that?

WAXMAN:
Yeah, I think that's wrong. Even though Hamas has committed a massacre, massacre on a massive and just monstrous scale, that doesn't absolve Israel of following the rules in its response, in the conduct of its own war of self-defense.

Now the fact that Hamas deliberately seeks to blur the distinction between its forces and civilians ... It uses human shields. It puts civilians in harm's way. It seeks to pervert the laws of war in order to gain an advantage in combat. That again ... it still doesn't absolve Israel of its responsibility to follow the law.

Moreover, we're talking about urban combat in one of the most densely populated areas on the globe, and that's always going to create challenges for a military force. No matter how well-trained and indoctrinated in international law it may be, it's going to be impossible to conduct operations without, in some cases, causing very, very tragic civilian death and destruction. But again, the key idea there is whether or not that civilian harm is intended or not. It can't be used to terrorize the civilian population. It can't be used as collective punishment. But the laws of war are intended to make war more humane but not make it humane.

LINDSAY:
I want to come back to this idea of collective punishment. But first, I want to just ask one more question about this issue of distinction. Does international law, whether formal or customary, give any guidance to states on how to proceed when your adversary is in fact using civilians as shields, is taking hostage, is trying to do everything it can to maximize the chances that your attacks will kill innocents?

WAXMAN:
Yeah, so international law does impose some requirements on a military force that is conducting operations against another one that is seeking to exploit or pervert the laws of war for its own advantage. You know, when an entity like Hamas uses human shields, when it encourages civilians to stay in harm's way, it really can gain one of either of two advantages. Either Israel will refrain from striking the target, therefore immunizing that target from destruction, or if Israel goes ahead and does strike it and causes collateral damage, then Hamas gains some advantage in the court of global opinion. So this is ... I think one of the challenges of the law of armed conflict is a lot of the rules are premised on the idea that both sides are trying to protect their own civilian population. When one of them does breach that basic obligation, it causes some real challenges for compliance.

And the last point I'll just make is even if Hamas uses human shields to try to immunize targets, if it does try to encourage civilians to remain in harm's way, rather than heeding warnings to evacuate a particular area, the IDF, the Israel Defense Forces, still must comply with the rule, the principle of proportionality. You still have to make this assessment that the anticipated civilian harm isn't excessive in relation to the anticipated military gain.

LINDSAY:
Well, let me ask you about this issue of collective punishment because I'm sure you have seen a lot of commentary criticizing Israel for what is alleged to be collective punishment against the people of Gaza by imposing a siege on Gaza after the October 7th reports. The Israelis also told 1.2 million Gazans to relocate to the south within twenty-four hours. There's been some criticism of that. I note that the International Committee of the Red Cross said that the move was not compatible with international humanitarian laws. I've heard people respond by saying, "But international humanitarian law also says you're supposed to give civilians warnings if at all feasible." How do you assess that?

WAXMAN:
Yeah, so maybe we could take those one at a time and talk about the siege and then talk about the evacuation order, even though, as you say, they're connected. With regard to siege, I would say first that it's hard to draw clear conclusions on this because the law of siege is contested, and Israel's policy here has been shifting over time.

You know, initially, at the beginning of the war, Defense Minister Gallant said Israel was going to cut off anything, everything going in and out of Gaza. That's been loosened over time—especially for humanitarian assistance, food, water. And I think that's a very good thing both morally and legally. Actually, it's also a good thing strategically. 

The split of opinion among international lawyers really turns on intent. There's one view that says that any starvation, for example, any type of mass deprivation of the civilian population is illegal. I think the better view—the view that the United States military, Department of Defense, takes for example—is that it depends a lot on intent and military necessity. That here, you know, you couldn't use siege to terrorize a population. You couldn't use it to impose some sort of collective punishment. But if cutting off certain resources, and here I draw a distinction between, for example, electricity, which is often referred to as a dual use target. Obviously it powers sanitation systems, hospitals, but it's also vital to military forces in waging war, including Hamas's.

But if a siege cuts off some of those militarily essential resources is necessary to wage war effectively, and it complies with the principle of proportionality that the anticipated military gains are very, very high and exceed the anticipated civilian harms, then siege can be justified as legal. I think one of the main points I just leave you with here is that I think the swift condemnations of Israel's siege as illegal are at best premature. I think they're based on very questionable interpretations of law, and this is something that we've seen throughout the conflict is I think some snap judgments that are made before all the facts are in.

LINDSAY:
Well, I think there's a great tendency, particularly on Twitter, to make snap judgments on all issues before the facts are in. So this is just a particular example of a broader human phenomenon. But Matt, I'm curious. Under international law, is there a specific definition of what constitutes a siege? I ask that because as I think about the history of warfare, countries have often sought to stop the supply lines of their adversaries. I go back to the British attempts during World War I, which were quite effective, to cut off the ability of Imperial Germany to use the siege to get imports. Obviously during World War II, the Germans tried to indite British supply lines. So where do you draw the dividing line between legitimately interdicting your adversary's supply lines in what constitutes a siege? Or is that simply undefined in international law?

WAXMAN:
I don't think the law in this area is well-defined. I think the key concept is, as you say, the idea of coordinating off an area in order to deprive the enemy military force of resources that are essential to its waging war effectively. This is a way of neutralizing the effectiveness of the other side and distinguishing that from efforts to deliberately, let's say, starve the enemy population, to terrorize it, or as we've talked about already, to impose some sort of collective punishment on the civilian population writ large.

And I think the best interpretation of international law in this area would draw distinctions based heavily on intent. I think also the legality of siege can also depend on what kind of resources we're talking about here. And I think one reason why it's important that Israel has allowed in, is allowing in, more humanitarian aid is ... that's, I would say, probably the most questionable of the kinds of resources that could be cut off in a siege. And it also helps to address that proportionality concern. It helps to minimize the civilian suffering that might result incidentally in an effort to try to deprive the enemy military forces of resources. And this starts to relate to the other issue we started talking about, which is the so-called "evacuation order" of northern Gaza.

LINDSAY:
So what is the status, in your view, of that evacuation order against the backdrop of, again, the UN secretary-general saying that Israel is engaged in collective punishment?

WAXMAN:
Yeah, here again, I'd say that I think the snap judgments were wrong. First of all, I think it's been mislabeled an evacuation order. What Israel did was warn civilians of Gaza to leave their homes in the north and go south within twenty-four hours. Now, the idea of moving a million people roughly in twenty-four hours was never realistic, and Israel has appropriately extended, by a lot, that deadline. But it was warning civilians to leave their homes in the north. I said it's kind of a misnomer to call it an evacuation order in that Israel doesn't govern northern Gaza. It's ordered evacuations of northern and southern Israel because it does govern, but what it's done here is warn civilians. And, you know, there's some irony that Israel is being accused of violating the law of armed conflict in issuing these warnings in that I think there's a good argument that it was required under international law to do so.

Again, northern Gaza is one of the most densely populated areas on earth. It was militarily... It is militarily necessary for Israel to engage in military operations against Hamas targets in northern Gaza. And so urging civilians to leave that area is a way of minimizing or reducing civilian harm. I think there are a couple of other just important aspects of it. I think it's important, and I would say necessary under international law, that this is not—and I've seen no evidence of this—this is not an effort to permanently depopulate northern Gaza. It's not intended as collective punishment of civilians so much as an effort to protect them. ... And that steps are being taken—again, like the opening up some crossings, allowing in humanitarian assistance—in order to try to reduce the human suffering that comes with an operation like this.

LINDSAY:
Matt, I want to return to the question of proportionality. Because I've seen a lot of talk in the news coverage and certainly on—I was calling it Twitter, I should call it X—about the relative death tolls suffered by Palestinians in Gaza compared to the number of people who have died in the attacks on October 7th in Israel. So I'm trying to understand this concept of proportionality. It's not, as I understand it, that proportionality is the number of losses you suffer in an initial attack relative to the number of casualties you inflict. It's rather about the proportionality of the strikes you undertake, if that makes sense.

WAXMAN:
Yeah, that's exactly right, and a very important clarification because I think the principle, the rule of proportionality, is often misstated in reports, in media coverage, in the kind of allegations of illegality or war crimes that we've seen. The principle of proportionality is not some macabre comparison of body counts: that Hamas killed this many people, so Israel is only allowed to kill this many people in response. That's not how it works. The question for commanders is, "What is the military advantage that I reasonably expect to gain from an action, a military action, and is that far outweighed by the civilian harm that I reasonably expect to cause?" That's the proportionality principle. It's a comparison of expected military gain and anticipated civilian suffering. And that, as I say, is often misstated and misstated quite badly in press coverage.

LINDSAY:
Okay. I think it's clear to stress this is not to deny the very real human suffering that we're witnessing in Gaza and that we saw in Israel with the attacks on October 7th. I'm trying to get to the core idea underlying these issues of the laws of war.

WAXMAN:
Yeah, and, you know, I would just emphasize that point, that I'm talking here about the law of armed conflict and compliance with that law. That doesn't deny in any way the reality that in a conflict like this there is unfortunately, tragically, a lot of civilian suffering, a lot of civilian death. That's a reality of urban combat generally. And it's a horrible, horrible aspect of this conflict.

LINDSAY:
Matt, I want to ask you, who gets to make the decisions about proportionality in terms of launching any military attack? Do the Israelis essentially get to grade their own homework? Are there objective standards that their activities are supposed to be compared against? Does Israel have a process of sort of reviewing and asking questions about its military activity? I know you served in the U.S. government. The United States does have a legal process for assessing the value of drone attacks, for example.

WAXMAN:
That's right. And I would say that first and foremost, the rule or principle of proportionality is something that is applied, conducted by the military forces themselves. It's an obligation on commanders or those who are directing military operations. And Israel trains and indoctrinates the IDF in international law, in Israeli law, in well-developed code of ethics. That's not to say that there aren't mistakes, even sometimes infractions. That's the reality of most high-intensity combat operations, though not all infractions amount to war crimes.

Beyond the training and doctrine that's involved and the kinds of internal processes to calculate anticipated civilian harm, weigh that against anticipated or expected military gain, there are other mechanisms that I think lead to pressure or even enforcement of international law. Some of the most important are sort of the informal processes: the political costs, the diplomatic costs, sometimes sanctions that might be levied against a state that's seen as violating this principle.

And in some cases, it could come before a court. It could come before a national court. And Israel is a state that has a very well-developed domestic system of compliance and enforcement of the law of armed conflict. And then of course, it's possible that these kinds of allegations could come before an international court, like the International Criminal Court. I'll just say that proportionality tends not to be prosecuted for the simple reason that it's so difficult to measure what I mentioned before, you know, to calculate humanitarian suffering and military necessity. These are very difficult to reduce to simple calculation that could be compared.

LINDSAY:
I'm glad you raised the issue of the ICC, the International Criminal Court, Matt. Could the ICC bring Israeli officials or charge Israeli officials given that Israel is not a signatory to the Rome Statute? And I'll just note, neither is the United States nor Russia.

WAXMAN:
That's right. The International Criminal Court, the ICC, could bring charges, could prosecute Israeli officials or Hamas members for war crimes. The ICC is an international court in the Hague set up to prosecute the most serious war crimes, crimes against humanity. As you said, Jim, neither the United States nor Israel are parties to this court, though the court has nevertheless, and very controversially, accepted jurisdiction over the situation in Palestinian Territories, including Gaza. I say it's controversial because Israel is not a party. It's controversial because Israel has its own well-developed systems of justice and accountability at the national level. And it's controversial because the ICC itself has accepted the idea that Palestine is a state and could therefore request jurisdiction.

LINDSAY:
Well, Palestine is a signatory to the ICC and has been since 2015, I think, which means that Hamas clearly would be subject to the ICC. Correct?

WAXMAN:
That's right. Although the very concept that Palestine is a state is a contested one. And the ICC has accepted that, but other UN bodies, many states around the world, have not accepted that idea. And I would just note that there's an important asymmetry here among many other asymmetries in this conflict, that you have one side that's trying to abide by the law of armed conflict while the other is seeking to exploit it. And Israel would care a lot if some members of its government were brought before this court, whereas I don't think Hamas would care one bit.

The last point I would just make on this, this is just my own opinion, but I think any action by the International Criminal Court in this conflict, especially against Israeli officials, would not actually be helpful to achieving a just and lasting peace. I think it's much more likely to harden the positions of the various parties to the conflict. I think many proponents of the International Criminal Court tend to wish away some tension between the goals of international justice and the goals of peace. And I acknowledge that in some cases those two goals may be entirely consistent, but they are not always, and sometimes there are important trade-offs between them.

LINDSAY:
Well, I would certainly note that if the ICC is going to inject itself in this matter, it clearly needs to also look at the actions of Hamas, which with its October 7th operation clearly, by any reasonable definition of international law or moral principle, violated international humanitarian law.

WAXMAN:
Yeah, I'd go even further, Jim. As your question suggests, the attacks, the massacre, October 7th, violated international law, was a war crime in a number of ways; the taking of hostages, the barbaric killing of babies, these are clearly war crimes. And I work a lot on war crimes and even by the savage standards of war crimes, this really stands out as especially barbaric, and a set of crimes also carried out with genocidal intent.

LINDSAY:
And we have video evidence of a number of the attacks. I don't want to lose sight of that. One final question, Matt, is I keep hearing arguments that we're seeing crimes against humanity being committed. I don't know if crimes against humanity has any status in international law. So does it, and if so, does it apply here?

WAXMAN:
It does apply here... Or it does have status in international law. I think the more relevant body of law is the law of armed conflict and the body of law that establishes war crimes. And I would just note one technical issue, but it's an important one, which is that not all infractions of the law of armed conflict constitute war crimes. It's the most serious ones. The Geneva Conventions, for example, talk about grave breaches of its rules. It's the most serious ones that constitute war crimes.

LINDSAY:
On that note, I'll close up The President's Inbox for this week. My guest has been Matthew Waxman, adjunct senior fellow for law and foreign policy at the Council, and the Liviu Librescu Professor of Law at Columbia Law School. Matt, again, thank you for joining me and explaining these concepts.

WAXMAN:
Thank you, Jim, for having me on.

LINDSAY:
Please subscribe to The President's Inbox on Apple Podcasts, Spotify, wherever you listen, and leave us a review. We love the feedback. If you want to reach out to us, please email us at [email protected]. Again, that is [email protected]. A transcript of our conversation is available on the podcast page for The President's Inbox on CFR.org.

As always, opinions expressed on The President's Inbox are solely those of the hosts or our guests, not of CFR, which takes no institutional positions on matters of policy. Today's episode was produced by Ester Fang, with Director of Podcasting Gabrielle Sierra. Special thanks go out to Michelle Kurilla. This is Jim Lindsay. Thanks for listening.