The legal uncontested claim of Israel to the Jewish Land in the Mandate for Palestine-Israel
When the U.N. passes a resolution it is only a recommendation. If accepted by the parties it becomes a valid agreement and or Treaty.
In the case of Israel and the Arabs, the U.N. passed a resolution in 1947 for the creation of a Jewish State and an Arab State. The Arabs did not accept the U.N. resolution of 1947 for a Jewish State and an ArabState. Thus the resolution is not binding. As such Israel's rights to the land falls back to the terms in the San Remo Treaty of 1920 which delineated The Mandate for Palestine to the Jewish people with all its terms without any deviation.
If anyone is contesting the legitimacy and sovereignty of the territorial boundaries assigned based on the San Remo Treaty of 1920 and the Treaty of Sevres of 1920 Article 95. You now have to contest and question the legitimacy and sovereignty including the territorial boundaries of the 21 Arab State created by the same Allied powers including Transjordan (Jordan).
Therefore if you accept the 21 Arab State and Jordan as assigned by the Allied Powers after WWI, you must accept Israel's sovereignty and boundaries as stated in the San Remo Treaty. The San Remo Treaty of 1920 assigned the Mandate for Palestine entirely which includes Jerusalem to the Jewish people. The terms of the San Remo Treaty of 1920 are valid in perpetuity.
President - Americans for Safe Israel in Greater Los Angeles