The most important power that Congress holds is the sole authority to enact legislation, meaning it is the only branch of the federal government that can make new laws or change existing laws. This legislative power is granted explicitly by the Constitution in Article I and is fundamental to Congress's role in governing the United States

. In addition to lawmaking, Congress uniquely holds the power to declare war, which is a significant check on the executive branch's military authority

. Another critical power is the "power of the purse," where Congress controls financial and budgetary matters, including laying and collecting taxes, appropriating funds, and authorizing government spending

. Congress also exercises substantial oversight and investigative powers over the executive branch, including the authority to confirm or reject presidential appointments (Senate), ratify treaties (Senate), and impeach and remove federal officials (House initiates impeachment, Senate tries impeachments)

. Among these, the legislative power to make laws is generally considered the most important because it underpins all other governmental functions and checks and balances. Without the ability to enact legislation, the other powers of Congress would be significantly weakened