Politics in Minutes (2016)
The legislature or parliament in most democratic countries is divided into two houses, or chambers. The two-chamber, or bicameral, system evolved from the medieval European parliaments, which had separate assemblies for the aristocracy and the commoners. Some modern democracies still have unelected upper houses, with appointed or hereditary members, while presidential republics tend to have two houses with roughly equal powers but elected in different ways, such as the US Senate and House of Representatives.
The advantage of the bicameral system is in the enactment of laws, which requires the approval of both chambers. This helps to provide a moderating force of ‘checks and balances’ that prevent bad laws from being passed. Although bicameralism is widely considered an important feature of democratic government, there are some who point out that it often acts as an obstacle to radical legislation, and so can prevent necessary political reform.
President Obama addresses a joint session comprising both houses of the US Senate.