More than 1900 Palestinians have been killed in Gaza, hundreds of thousands are displaced and the material destructions are formidable. There have been several claims that Israel has violated international law. But the focus is only on violations of international humanitarian law (jus in bello), not on breaches of restrictions following from the right of self-defence (jus ad bellum).

This was similar after the previous Israeli invasion of Gaza, “Cast Lead” in 2008-2009. The Goldstone Commission’s mandate, established by the Human Rights Council, was to examine possible breaches of international humanitarian law and human rights law. The International Red Cross (ICRC) supervises compliance with international humanitarian law. Human Rights Watch in its Q&A: 2014 Hostilities between Israel and Hamas seems at least to be aware of the problem, by saying that it does not address “the legitimacy of resorting to armed force, such as under the United Nations Charter.”

But the use of military force is restricted both by international humanitarian law and jus ad bellum. This was recognized by the International Court of Justice in the Wall case (para. 42). Israel has under article 51 of the UN Charter a right of self-defence against the rocket attacks from Hamas. This right was claimed by Israel as a legal basis for the Cast Lead operations (Cast Lead: The Operation in Gaza. Factual and Legal Aspects, July 2009, para. 68. See also the Goldstone report, para. 187.). But it is generally accepted that this right is subject to restrictions of necessity and proportionality.

The requirements of proportionality are different in international humanitarian law and as a restriction on the right to self-defence. David Kretzmer explains the difference (The Inherent Right to Self-Defence and Proportionality in Jus Ad Bellum. 24 EJIL (2013), 235-282, at 278):

While the question in jus in bello relates to attacks on specific targets, in jus ad bellum the question relates to the whole picture. Use of force could conceivably be disproportionate under jus ad bellum even if all specific attacks met the demands of proportionality in jus in bello. The jus in bello test refers to collateral damage to civilians or civilian objects which are not in themselves legitimate targets, whereas the jus ad bellum test includes (but is certainly not confined to) damage to combatants and military objects.

The restrictions on self-defence for Israel’s military operations should receive more attention. What are the limits for these operations? Has Israel gone too far?