A second aspect of the core value of constitutional government is separation of powers.
The constitution divides government into three branches by function--legislative, executive, and judicial. Powers and officers for each branch must be appropriate for the end served by each branch.
The separation of powers helps preserve our liberties. According to James Madison in Federalist 47, "No political truth is certainly of greater intrinsic value or stamped with the authority of more enlightened patrons of liberty" than the idea of separation of powers. "The accumulation of all powers legislative, executive, and judiciary in the same hands, whether heredity, self-appointed, or elective, may justly be pronounced the very definition of tyranny."
The failure to maintain this distinction between branches of government in Britain had been one of the complaints about British rule--albeit a minor one. British monarchs, limited as they were, greased the legislative process in Britain through influence. They would offers member of the House of Commons pensions or paid military commissions to sway their votes in support of the king's program. In addition, they would add peers to the House of Lords by granting titles of nobility in return for support. The origins of the term "political corruption" came from this practice of "corrupting the legislature."
The constitutional, however, does not separate the branches completely. Each branch possesses the constitutional means to resist encroachments from the others. "Ambition must be made to counteract ambition."
The most difficult challenge was controlling the legislative branch. Contrary to what you and I were told in high school civics, the Constitution did not separate powers into three co-equal branches. A glance at the Constitution and the relative space devoted by each article to the separate branches demonstrates the differences. As Madison wrote in , in Federalist 51, "in republican government, the legislative authority, necessarily, predominates."
So how does the Constitution propose to control the government's most powerful branch, the legislature?
It creates a legislature of two different houses to check and balance each other.