interests. Greater representation given to small states in the Senate and the Electoral College, "first-past-the-post" voting, gerrymandering, etc.—have in recent years had a more extreme effect and have begun to create a disconnect between what the government does (in legislation and court rulings) and what the majority of Americans want. (... and has for the last six years.) Democratic backsliding concerns have led to some academics on the other hand to warn that thanks in part to the rulings of the Supreme Court, the U.S. is already a one-party state, and no longer meets the minimum requirements to be considered a democracy. Federal government The United States is a constitutional federal republic, in which the president (the head of state and head of government), Congress, and judiciary share powers reserved to the national government, and the federal government shares sovereignty with the state governments. The federal government is divided into three branches, as per the specific terms articulated in the U.S. Constitution: The executive branch is headed by the president and is independent of the legislature. Legislative power is vested in the two chambers of Congress: the Senate and the House of Representatives. The judicial branch (or judiciary), composed of the Supreme Court and lower federal courts, exercises judicial power. The judiciary's function is to interpret the United States Constitution and federal laws and regulations. This includes resolving disputes between the executive and legislative branches. The federal government's layout is explained in the Constitution. Two political parties, the Democratic Party and the Republican Party, have dominated American politics since the American Civil War, although other parties have existed. There are major differences between the political system of the United States and that of many other developed countries, including: an upper legislative house (the Senate), with much more power than is found in equivalent bodies in most other countries; a Supreme Court that also has a wider scope of power than is found in most countries; a separation of powers between the legislature and the executive; and a political landscape dominated by only two main parties. The United States is one of the world's only developed countries where all additional parties have minimal or nonexistent influence and almost no representation at the national and state level. Causes for this mainly focus on the plurality-based first-past-the-post voting system, used in most elections, which encourages strategic voting and discourages vote splitting. This also