Such a capability is the sine qua non of a superpower and is essential to the credibility of our overall national security strategy.

CENTERFORSECURITYPOLICY: Center for Security Policy | The Measure of a Superpower: A Two Major Regional Contingency Military for the 21st Century

Somehow... the idea of the public plan became the sine qua non of meaningful reform for a very vocal portion of the Democratic intellectual elite.

BBC: Obama may soften healthcare plan

Bill Clinton, who is not French, and who came into office calling for the discontinuance of heavy echelons in favor of power projection, simultaneously pressed for a severe reduction in aircraft carriers, the sine qua non of power projection.

CENTERFORSECURITYPOLICY: Center For Security Policy

In the debate over climate legislation in 2009 and 2010, it was conventional wisdom that a price on carbon was the sine qua non of effective climate policy.

FORBES: The Carbon Tax, Then and Now

The general feeling among the delegates at the conference was that the breaking down of barriers is a sine qua non.

UNESCO: WHO IS THE OTHER?

The single most important quality of a leader, the sine qua non, is absolute professional integrity.

FORBES: Scott Thompson, Resumes And Rodents

The injured extremities hold a bottle of 2007 Labels Syrah from California's worshiped Sine Qua Non winery.

WSJ: Welcome to a Hedonist World | Yevgeny Chichvarkin and Hedonism Wines

So ostensibly then, big bonuses are a sine qua non if all these essential executives are to keep their apparently non replaceable skill sets in the service of AMR Corp.

FORBES: Gag Order Placed On American Airlines Employees

Or to put it another way, banking union might be a precursor to the kind of fiscal and balance-sheet union that is widely regarded as the sine qua non of eurozone survival, but that supposedly vital financial union has not happened yet.

BBC: Eurozone banking union that works for Britain?