Speaking specifically of the topic of this thread -- the laws of "occupation" demand that the territory in question be under the sovereignty of one entity in order to be occupied by another. Since Arab Palestine has never been a sovereign entity, it CAN NOT, by definition be "occupied".
Canada, agreeing with UN Security Council Resolutions 446 and 465, argues that the Fourth Geneva Convention applies to the occupied territories (the Golan Heights, the West Bank, East Jerusalem and the Gaza Strip) and that Israeli settlements are a violation of the Fourth Geneva Convention.
occupied territories violate international law - Google Search
Sigh. The Fourth Geneva Convention does not apply because there is no occupied territory. There have been only three sovereigns in the territory since the end of the Mandate: Israel, Jordan and Egypt. Jordan and Egypt NEVER had any legal claim to the territory, and even if they did -- they renounced all claim to the territory in the peace treaties with Israel. (Which, btw, set borders between themselves and Israel.)
Which leaves us with only two options: The territory belongs to Israel. Or the territory is terra nullius. There is no third option.