In case I decide to blog about whether Israel's actions are in accordance with international law, I've decided to lay out the basic facts. I'll try to keep it brief and simple, so if I leave something out that's to be expected. Moreover, it's been a few years since I really used to follow this stuff, so I'll be working from memory and old papers on my computer. Bear with me. Also, none of this information is mine and I will try to cite where appropriate.
The basic structure of international law is laid out in Article 38(1) of the Statute of the International Court of Justice, which lists the four sources of international law:
1) International conventions
2) international custom, as evidenced by general practice
3) The general principles of law recognized by civilized nations
4) The opinions of the highly regarded scholars of international law.
International law in relation to the territories
Israel has signed both the Hague Convention of 1907 and the Fourth Geneva Convention of 1949. Both these conventions govern the responsibilities of the occupying power in relation to the occupied people.
The application of these conventions to the West Bank and Gaza is a matter of dispute. In the famous Beth-El case the Israeli Supreme Court ruled that the Hague Conventions constitute international custom and are binding on the military government. The Court, however, has consistently refused to apply the Geneva Conventions to the territories.
The official Israeli government position is that the Geneva Conventions do not apply because the wording of the convention itself presupposes the existence of a sovereign reversioner, a country from which the territory was captured. This argument is best laid out by Meir Shamgar, who was the Chief Justice of Israel's Supreme Court in the early 90's, and Yehuda Blum, who served as Israel's UN ambassodor in the 80s. Shamgar, serving as Attorney-General in 1968, formulated Israel's position vis-a-vis the Genenva Conventions, while Blum argued Israel's position as to its status in the territories.
Is Israel an Occupying Power?
The short answer is technically no. To be an occupier, there must be a country from which Israel took the West Bank and Gaza. Egypt admitted it did not have sovereign rights over Gaza; Jordan annexed the West Bank (hence the name "West Bank"), but Jordan's acquisition stemmed from aggressive war and every legal scholars admits that land cannot be captured in aggressive war. So there was no "sovereign reversioner."
Could the Palestinians constitute the sovereign reversioner? Doubtful. They never had sovereignty over either the WB or Gaza and Israel did not capture the land in a war with them. The Palestinians were never parties to the Six Day War in a legal sense. Since the Hague Conventions require that for a land to be occupied it must be "placed under the authority of the hostile army" (Article 42), a belligerent occupation can only stem from a war between two warring countries. Such is not the case between Israel and the Palestinians.
There are other arguments, but I want to keep this post short.
The Geneva Conventions
Article 2 of the Geneva Conventions lay out when the conventions apply. Article 2(2) states
"The Convention shall also apply to all cases of partial or total occupation of the territory of a High Contracting Party, even if the said occupation meets with no armed resistance. "
Article 2(1) speaks of the conventions application during the actual conflict. When the conflict ends, the conventions only applies if the occupation is of the territory of a high contracting power. While Jordan and Egypt were both high contracting parties, the territory captured did not belong to them. Since the application of the conventions is conditioned on the territory occupied being the sovereign property of the high contracting parties, and Jordan and Egypt did not fulfill this condition, it follows that the conventions do not apply.
This analysis is bare, but for simplicity's sake I'm going to leave it off here.