sine qua non

“Nevertheless, in consideration of the very grave difficulties which would result from opening up the whole case again, the majority of the commission held that they might and should abide practically by the testimony of the official documents and especially by that of the minister I, yonne regarding the reality of the "subscription pure and simple", at the same time emphasizing anew this point as the essential basis and the condition sine qua non of peace.”

The Catholic Encyclopedia, Volume 8: Infamy-Lapparent

“Significantly for Lebanon, the Quartet’s hardest issue to resolve was its own final statement a statement being the sine qua non of a successful meeting in UN-land and diplomacy generally on armed groups such as Hamas participating in the upcoming Palestinian elections.”

Simon & Schuster: Surrender is not an Option

“Now Churchill learned that it was Bonar Law who was the arbiter of his fate and that his own removal from the Admiralty had been the sine qua non in discussions between Asquith and Bonar Law about the formation of a coalition government.”

Castles of Steel

“Great Britain to destroy our government (of which Henry's is but one sample), and with the Indians to tomahawk our women and children, prove that the cession of Canada, their fulcrum for these Machiavelian levers, must be a sine qua non at a treaty of peace.”

Letters

“This ten-and-a-half-millimeter-diameter lifeline is a sine qua non of my escape from Blue John Canyon.”

Simon & Schuster: 127 Hours

“Never to allow a patient to be waked, intentionally or accidentally, is a sine qua non of all good nursing.”

Notes on Nursing: What It Is, and What It Is Not