Israel took control of and occupied the West Bank and the Gaza Strip after the 6 Day War in June 1967. The legal adviser to the Israeli government, Theodor Meron, delivered an opinion on a question asked by the Prime Minister's Office regarding the legality of civilian settlement in the West Bank and Gaza Strip. His conclusion, simply stated in the cover note to the opinion, was that "civilian settlement in the administered territories contravenes explicit provisions of the Fourth Geneva Convention".
Please click on the hyperlink to read a translation into English of the opinion from the original Hebrew by a professional legal translation company.
"Settlement in the Administered Territories, 18 September 1967": 1967 Meron opinion (pdf; 26kb)
Original source: Israel State Archives, 153.8/7921/3A. Legal opinion numbered as document 289-291, with unnumbered cover notes (Hebrew)
A copy of the original opinion in Hebrew, has kindly been made available by Gershom Gorenberg, author of The Accidental Empire: Israel and the Birth of the Settlements, 1967-1977, (Times Books) and can be viewed at: southjerusalem.com/settlement-and-occupation-historical-documents/