Which branch of the U.S. government has the power to declare war?

The branch of the U.S. government that has the power to declare war is Congress. This authority is established in Article I, Section 8 of the U.S. Constitution, which explicitly grants Congress the power to declare war. This provision is part of the Framers' intent to ensure a system of checks and balances, whereby Congress, as the legislative branch, plays a crucial role in decisions that involve military conflict.

While the Executive branch, particularly the President, can lead the military and direct operations once a war is declared, the initial decision to engage in war must originate from Congress. This power to declare war reflects the Founding Fathers' caution regarding the concentration of military power in the hands of a single individual. Therefore, having Congress hold this power allows for broader representation and involves the elected representatives of the people in matters of national security.

The Judicial branch does not have the authority to declare war, as its role is to interpret laws and determine their constitutionality, rather than to engage in decisions about military action. Additionally, state governments lack the power to declare war, as military authority and foreign relations are reserved for the federal government at the national level to maintain unity and coherence in matters of national defense.