Here is a section from Principles of International Law, by Hans Kelsen, 1952:
The principle that enemy territory occupied by a belligerent in course of war remains the territory of the state against which the war is directed, can apply only as long as this community still exists as a state within the meaning of international law. This is hardly the case if, after occupation of the whole territory of an enemy state, its armed forces are completely defeated to that no further resistance is possible and its national government is abolished by the victorious state. Then the vanquished community is deprived of one of the essential elements of a state in the sense of international law: an effective and independent government, and hence has lost its character as a state. If the territory is not to be considered a stateless territory, it must be considered to be under the sovereignty of the occupant belligerent, which—in such a case—ceases to be restricted by the rules concerning belligerent occupation. This was the case with the territory of the German Reich occupied in the Second World War after the complete defeat and surrender of its armed forces. In view of the fact that the last national government of the German Reich was abolished, it may be assumed that this state ceased to exist as a subject of international law. If a belligerent state ceases legally to exist as an effect of the defeat, as, e.g., the Austro-Hungarian Monarchy in the First World War, or the German Reich in the Second World War, no peace treaty or any other treaty can be concluded with this state for the purpose of transferring the territory concerned, or parts of it, to the victorious or any other state.
On the territory of the abolished state a new state or some new states may be established. This was the case with the territory of the defeated Austro-Hungarian Monarchy, which was the territory of two united states. On this territory the Czechoslovakian and the Austrian Republics, and part of Poland have been established. This is also the case with the territory of the German Reich on which two new states came into existence; the western German state, called the Federal Republic of Germany; and the eastern German State, called the German Democrat. Republic. But the new state or the new states, which have not been at war with the victorious state, cannot conclude a peace treaty and are not entitled to dispose of other territory but their own. That the Austrian Republic was forced to conclude a peace treaty with the Allied and Associated Powers, although this new state was not at war with the states which by their victory brought the Austro-Hungarian Monarchy to dismemberment, and that the Austrian Republic was forced to dispose in this treaty of territory of the disappeared state which never was territory of the Austrian Republic, was based on the fiction that the Austrian Republic was identical with the Austrian Monarchy. In the case of the German Reich, the governments of the occupant powers maintained the fiction; that it continued to exist even after the abolishment of its last national government, and on the basis of this fiction it was assumed that the territory of the German Reich occupied by the four victorious powers was not under their sovereignty, but remained under the sovereignty of the German Reich. But the administration of the occupied territory was in no way in conformity with the rules concerning belligerent occupation.It sounds like Kelsen is arguing that Israel wouldn't have had any legal obligation to follow the Geneva Conventions laws of occupation in the territories. They were not considered Jordanian or Egyptian territory and they certainly weren't "Palestinian". To apply the humanitarian components of Geneva is proper, of course, and Israel voluntarily did so. But this sounds to me that even if you hold that the prohibition of "transfer" of a population to the territory includes voluntary relocation, that this would not apply to the West Bank or Gaza after 1967.
So would modern legal scholars say that Kelsen was wrong in 1952? Or is he only wrong retroactively, now that the rules were re-interpreted to damn Israel?
I emailed this question to a couple of well-known international law experts. One said that there was no clear rule before 1967 about the occupation or conquest of non-sovereign territory, and the rules that are bandied about today are clearly applied uniquely for Israel. The other stated that before 1967 it was "blindingly obvious" that the laws of belligerent occupation would not apply to non-sovereign territory, "exactly the opposite of what everyone says about Israel today."
Who says international law doesn't change? What used to be OK is now forbidden - because Israel is considered guilty at the outset.