The second key point is that American history is rich with examples of government officials doing what the F.D.A. decided not to do in this case: overhaul their process in a time of crisis.

Franklin D. Roosevelt repeatedly broke with tradition — and endured confrontation with the courts — to fight the Great Depression. His administration, working closely with business, also threw out the normal bureaucratic procedures to build World War II ships, planes, tanks, bombs and other matériel with stunning speed. In this century, the Federal Reserve under Ben Bernanke took creative risks that helped keep the financial crisis of 2007-9 from becoming another Great Depression. (The title of Bernanke’s memoir is telling: “The Courage to Act.”)

In each of the instances, officials avoided taking steps that clearly violated the law. Yet they recognized that the law often includes gray areas and gives government agencies leeway to choose one of several approaches. During normal times, taking the cautious route and following procedural precedent tends to make sense. It minimizes chaos and mistakes.

But a national emergency can change the equation.