The Constitution splits war-making authority: Congress declares war and funds the military, while the president serves as commander in chief. The Framers were deliberate about gives Congress authority over the decision to go to war with the: 

“The Executive is the branch of power most interested in war, and most prone to it”  –James Madison, Fourth President, popularly known as “Father of the Constitution” 

However, this balance has steadily eroded over time. Congress has formally declared war only 11 times, most recently in 1941. Since then, U.S. forces have fought in Korea, Vietnam, Iraq, Afghanistan, and dozens of other conflicts without a formal declaration.

Instead of formal declarations of war, presidents of both parties have committed troops by citing commander-in-chief authority or securing broad “authorizations for use of military force” that were far easier to stretch than a declaration of war.

The War Powers Resolution of 1973: Congress Tries to Take Back Control

After years of large-scale military involvement in Vietnam and across southeast Asia without a declaration of war, Congress passed the War Powers Resolution of 1973 over President Nixon’s veto. This legislation required the president to:

• Notify Congress within 48 hours of committing forces to hostilities 
• Withdraw them within 60 to 90 days if there’s been no congressional authorization 

In practice, it has not worked as intended: Every president since Nixon has questioned its constitutionality, and presidents have defined “hostilities” narrowly to avoid triggering the clock. 

The 2001 Authorization for Use of Military Force, passed after the September 11 attacks, became another example of authority hollowed out over time—stretched by successive administrations to cover operations in 19 countries against terror groups, including a number of groups that didn’t exist in 2001, and still unrepealed more than two decades later.

💡Why does this matter? War powers are a textbook illustration of the difference between what Congress’s powers look like on paper and what they look like in practice. Through a combination of presidential expansion, broad legal interpretations, and Congressional acquiescence, the country has effectively given one person enormous discretion to commit U.S. forces in ways that can lead to major wars.  As one analysis concluded, once Congress cedes this kind of power, it is “exceedingly difficult to take it back.” 

Constitutional powers remain real only if Congress actively uses them.