Who has the power to declare war according to the Constitution?

The Constitution grants Congress the authority to declare war, which includes both the Senate and the House of Representatives. This power is outlined in Article I, Section 8, where it explicitly states that Congress has the power "to declare war." This provision was established to ensure that the decision to engage in military conflict is a collective one, reflecting the will of the elected representatives of the people, rather than being vested solely in the executive branch.

The President, as the Commander in Chief of the armed forces, does have significant authority to direct military operations once war is declared, but the initial decision to declare war requires congressional approval. This framework is designed to provide a system of checks and balances between the legislative and executive branches of government.