Answer extracted from the 3 Takeaways™ podcast — listen to the full episode below.
How did the shift from a militia-based to a standing army change the balance of military power between president and Congress?
When the Constitution was written, there was no standing army—assembling one took weeks or months, giving Congress time to declare war before any action. Today, a president can order military action almost instantaneously. Congress gradually retreated from authorizing military force, and the executive branch filled the void, interpreting law to allow presidential deployment whenever important national interests are at stake, so long as it doesn't rise to the level of war in scope, duration, and purpose.
The constitutional design now obsolete
The Founders deliberately built friction into the war-making process. An armed conflict required assembling militia across states, a process that naturally forced deliberation and congressional involvement. Power hates a vacuum—when Congress became unable or unwilling to authorize military action quickly enough for modern crises, presidents began acting unilaterally, and the legal interpretation evolved to permit it.
This shift reflects a fundamental mismatch between eighteenth-century institutional design and twenty-first-century threats. As Jay Johnson explains in the episode, the executive branch now operates under an existing legal understanding that permits rapid military deployment without a formal war declaration, provided it aligns with broad national security interests.
Congressional retreat and executive expansion
Congress has declared war only five times in all of American history, and not once since World War II—yet the United States has engaged in major military operations in Korea, Vietnam, Iraq, Afghanistan, and elsewhere. This gap between constitutional design and modern practice reveals how thoroughly the balance has shifted.
When a crisis demands immediate response, the president acts first and Congress, if it acts at all, legislates after the fact. A point detailed in this podcast episode is that the legal framework has accommodated this reality by allowing presidential military action so long as it does not rise to the level of war in scope, duration, and purpose—a distinction that has proven elastic in practice.
"You rarely have all the facts before you have to make a decision. You had to make a judgment based on what you know and what you didn't know, and it was not going to get any better anytime soon."
Jay Johnson — Former Secretary of Homeland Security and General Counsel of the Department of Defense. Johnson advised multiple presidents on war, terrorism, and national security from inside the Situation Room, bringing decades of experience in the highest-level national security decisions and executive authority.
The real tension is not between constitutional law and executive practice, but between the speed modern threats demand and the deliberation the Constitution was meant to enforce. As Johnson notes in the full discussion, presidents often inherit a legal framework that permits action they may not have consciously chosen to claim—they inherit the accumulated expansions of their predecessors.
See also
Why has the U.S. military engaged in multiple conflicts without formal congressional declarations of war?
Congress has declared war only five times in American history and not once since World War II, yet America has fought in Korea, Vietnam, Iraq, Afghanistan, and elsewhere through executive military action without formal declarations.
How often do presidents have complete information before making life-and-death military decisions?
Lawyers want all facts before making a decision, but in national security you rarely have all the facts before you must act. Presidents must make critical decisions based on incomplete information and judgment about what remains unknown.
How should a leader manage the impulse to act immediately when responding to a crisis?
Leaders should deliberately assemble advisors with diverse risk tolerances and viewpoints—some aggressive and action-oriented, some cautious and methodical—and ensure all voices are genuinely heard together in the decision-making room.