Israel is not a party to Protocol I to the 1949 Geneva Conventions, governing the protection of victims of international armed conflicts. Nor, for that matter, is Hamas. The PLO, even before it was given formal authority as the Palestinian authority, committed to abide by Protocol I and the other Geneva Conventions, although for many years thereafter plainly violated these provisions by deliberately attacking civilians. As the successor government to Fatah in Gaza, it could be argued that Hamas is bound by the previous accession of the PLO, but since Hamas has rejected other Fatah agreements, it is not clear what the point of such an argument would be.
Although Protocol I is not treaty law binding on either Hamas or Israel, the principles it expresses are nonetheless sufficiently widely accepted that they could be considered norms of customary international law or jus cogens, that is, binding quite apart from any treaty obligation. And even if not, they are, in their content, admirable. Thus, in the court of public opinion, it is worth thinking about whether Hamas and Israel have abided by them.
For Hamas the answer is easy: Not even remotely. Deliberately targeting civilians, as Hamas missiles do---to the extent that they can be said to "target" anyone, given their unpredictability---violates humanitarian law. (Article 51(4) forbids "indiscriminate attacks.") So too does the Hamas practice of taking refuge behind civilian human shields. Israel does not target civilians, although Israel has killed a great many civilians as a "collateral" consequence of attacks on Hamas fighters in the current conflict. Although Protocol I does not forbid military operations that result in such collateral consequences, it obligates state parties to minimize such casualties. In particular, it contains a proportionality norm that forbids attacks "which may be expected to cause incidental loss of civilian life, injury to civilians, damage to civilian objects, or a combination thereof, which would be excessive in relation to the concrete and direct military advantage anticipated."
Here I want to make some observations about the proportionality norm:
1) Talking heads and others commonly talk as though humanitarian law requires that the overall military operation must be proportionate to the provocation. However, that is not true of international humanitarian law. If the use of force is justified in national self-defense (or authorized by the UN Security Council), then a nation may wage war against the aggressor nation. Here, Israel contends that Gaza (treated for these purposes as a nation governed by Hamas) has attacked Israel via rocket fire. That is a casus belli, and once war is justified, Israel has the legal right to attack the Hamas military, including its infrastructure.
2) Now, international law does appear to contain a different proportionality norm of roughly the sort that the talking heads have in mind: As the International Court of Justice said in adjudicating Nicaragua's complaint against the U.S. during the 1980s (which the U.S., while not showing up to defend itself, nonetheless tried to justify as collective defense in response to Nicaraguan incursions into Costa Rica, El Salvador and Honduras), armed self-defense or collective defense must be both necessary and proportionate. The ICJ judgment in that case did not reach the question of whether sponsoring the contras and mining Nicaragua's ports was disproportionate because it found no valid claim of collective defense, as no country had asked for American help in defending against Nicaragua. But the language there and in international law treatises does strongly indicate that self-defense justifying war does not entail unlimited war aims. As my colleague Jens Ohlin (co-author of Defending Humanity) explains (in an email to me): "the UK was justified in expelling Argentina from the Falklands, but invading the mainland and toppling its government would have been disproportionate."
3) Viewed in this light, Israel's principal war aim appears to be legitimate: to destroy or degrade the ability of Hamas to launch rockets into Israel. The matter is not entirely free from doubt, however, because Israel has not been entirely clear on its war aims. But the point I want to emphasize here is that the question of whether Israel's war aims are disproportionate to the casus belli is very different from the question of whether the collateral civilian casualties are disproportionate to the achievement of Israel's military objectives in attacking Hamas fighters. Or to put the point somewhat more tendentiously: There is no legal requirement that Israel's use of force be proportionate to Hamas's use of force.
4) If we think about these issues from the standpoint of morality, rather than international law per se, we might think that whether civilian casualties are proportionate depends ultimately on the value of the military objective. I have real doubts about the likely impact of the current operations by Israel. It seems to me that they will further radicalize Palestinians---not just in Gaza but also on the West Bank---and thus render less likely any lasting peace either with Fatah or with the less ideologically fanatical members of Hamas. And if the whole operation will, in the long run, decrease rather than enhance Israel's security, then it is hard to see how any civilian casualties are proportionate to the operation. However, that is not the legally relevant measure of proportionality. The legal norm of proportionality under international humanitarian law focuses more narrowly on the relation between civilian casualties and immediate military objectives. Killing Hamas fighters and commanders is a legitimate objective in a war that appears to have legitimate (if not necessarily wise) aims overall, and so the real open question is whether the suffering incidentally inflicted on the civilian population is proportionate to the achievement of that objective.
5) I honestly don't know the answer to that question. It is notoriously difficult to determine what counts as proportionate under humanitarian law, and some academics and judges think this renders the proportionality norm useless. To the extent that we can identify factors, the ratio of military to civilian casualties is certainly a relevant consideration, but other factors also come into play, including whether the enemy bears responsibility for mixing its forces among civilians. To be clear, the fact that Hamas uses human shields does not absolve Israel of the responsibility to minimize civilian casualties, but it may bear on what counts as a sufficient effort at minimization, and thus on what counts as proportionality.
6) Mostly unrelatedly, I have heard some defenders of the current Israeli operation point to the fact that Hamas was elected, and receives support from a substantial portion of the civilian population of Gaza. Thus, it is said, civilians in Gaza are reaping what they sowed. Whether this fact is morally relevant, it is certainly legally irrelevant. If the rule were otherwise, civilians in democracies could not count on the protections of humanitarian law. A civilian remains a civilian even if he is loyal to and supports his government, however odious that government's policies may be. Of course, a civilian who takes up arms but not a uniform ceases to be a civilian, and in so doing violates the law of war, but that is a different point entirely.
Posted by Mike Dorf