The Palestinians are likely to make Theodor Meron's Top Secret Memo exhibit A if the ICC decides to hold hearings against Israel. Meron, a Holocaust survivor with a doctorate in international law from Harvard, was one of Israel's top legal experts in 1967. When Israel's Foreign Ministry asked him whether it would be legal to settle in the territories captured in the Six Day War, Meron wrote an opinion that stated:
My conclusion is that civilian settlement in the administered territories contravenes the explicit provisions of the Fourth Geneva Convention.
It is clear from reading his memo that Meron didn't WANT to come to this conclusion, but his reading of the law, in light of how other nations interpreted the Geneva Convention, forced him to that conclusion. He concluded that Israel COULD establish military outposts in the administered territories, but they could only be temporary, not permanent.
Meron's opinion further sates
Even if we settle an army and not civilians, we must, from the point of view of international law, have regard to the question of ownership of the land that we are settling. Article 46 of the Hague Regulations concerning the Laws and Customs of War on Land (Annexes to the Hague Convention (IV) of 1907), regulations that are regarded as a true expression of customary international law that is binding on all countries, states in relation to occupied territory
"private property ... must be respected. Private property cannot be confiscated."
This is problematic considering that Israel hasn't been shy about kicking Palestinians off their land when it suits state needs.
I'm sure that Meron has heard every possible argument under the sun as to why his analysis is wrong. It would be hard for him not to have heard from a pro-settlement apologist spouting various legal theories during all these years. And yet, as recently as January 2015, he said the opinion he worte back in 1967 "still represents my best reading of international law."
See the following to read the Meron opinion and background information about the opinion.
The Etzion Illusion : The story of how the Israeli government ignored the Meron opinion and used subterfuge to establish the first settlement.
Also of Interest
Re: Geneva Convention: Blasting Homes and Deportation: Another Meron Memo saying that demolishing homes of terror suspects and deporting residents of East Jerusalem and West Bank on security gorunds violated the Fourth Geneva Convention