There was a Mandate. The purpose of that Mandate - and all the post-WW1 Mandates - was to prepare the people for statehood, because they were not regarded as "ready" to stand on their own. As Statehood was reached the Mandate expired in that territory. Jordan became a state, and so the Mandate lapsed east of the Jordan River in 1946. Israel became a state in 1948, and so the Mandate immediately lapsed in the territory that she claimed as her sovereign land. She did not claim the land outside of the '49 Armistice Lines, then or (bar Jerusalem) subsequently. Neither Israel nor Jordan could lay subsequent claims OUTSIDE of their own sovereign territory, coz ya' don't get TWO bites of the cherry. If that were possible then Jordan's annexation of the West Bank '49-'67 would have been legal, and it wasn't. Neither is Israel's post-67 claim to colonization rights in the WB, coz ISRAEL's Mandate-related rights ceased in '48.
Knesset passes 'Norwegian Law' allowing ministers to resign their seats, remain in cabinet (Haaretz)
from the article: Officials: Israel to allow construction in existing W. Bank settlements