Whakakīhia te rerenga e whai ake nei: I te tīmatanga o te tau 1948, i mahi a Henkin i te tari o te United Nations o te United States Department of State, i reira ko ia tētahi o ngā tāngata e kawenga ana mō te Convention Relating to the Status of Refugees i te tau 1951, he whakaaetanga i whakatūria ai te whakamāramatanga i whakaaetia i te ao whānui o te mea e hanga ana i te rerenga me te whakatūnga i ngā whakaritenga mō ngā whenua ki te whakarato i te whakarurutanga ki ngā tāngata kua tohua. I mahue ia i te tari State i te tau 1956 ki te whakaako mo te tau i te Whare Wananga o Columbia mo te kaupapa o te whakakorenga karihi i waiho hei kaupapa mo tana pukapuka 1958 "Arms Control and Inspection in American Law". I whakaako ia i te Whare Wānanga o Pennsylvania mai i te tau 1958, e haere tonu ana i tana mahi i whakaputaina hei "The
Berlin Crisis and the United Nations" i te tau 1959 me te pukapuka "Disarmament: The Lawyer's Interests", i whakaputaina i te tau 1964.