The Federal Government of Mexico is the national government of the state of Mexico. The government is a constitutional democracy and is based on a congressional system, whereby the President of Mexico is both head of state and head of government. Like many modern democracies, the Federal Government of Mexico consists of an executive, legislative and judicial branch. The Mexican state is governed under the constitution of 1917 and was adopted as a result of the Mexican revolution. The president of Mexico serves a six year term and is directly elected by the people. The bi-cameral legislature, known as the Congress of the Union, consists of 500 members and serves a 3 year term. Mexico is a federal state and consists of 31 states.