The three branches of U.S. government—legislative, judicial, and executive—carry out governmental power and functions. A-Z Index of U.S. Government Departments and Agencies Government departments, agencies, bureaus, commissions, committees, and offices Executive Branch The executive branch of the government is responsible for enforcing the laws of the land. The president, vice president, department heads (cabinet members), and heads of independent agencies carry out this mission. Judicial Branch Courts decide arguments about the meaning of laws and how they are applied. They also decide if laws violate the Constitution—this is known as judicial review, and it is how federal courts provide checks and balances on the legislative and executive branches. Legislative Branch Article I of the Constitution establishes the legislative or law making branch of government. It has a two-branch Congress—the Senate and the House of Representatives—and agencies that support Congress.