The US government is consisted of three branches, domes, and this is with the purpose that nothing manages to pass through without every aspect of it being reviewed to the detail by all sides. This is with the purpose that no political party manages to gain so much power in the decision making that the democratic process can be affected by it, so in the US government everything is triple checked and voted for.
The division of the US government into three branches is called "separation of powers" or a system of "checks and balances" to ensure that no one branch becomes too powerful.
