Before 1789, the U.S. had been ruled by the Articles of Confederation (1781) in fear of govt. abusing power (like British rule). In 1787, it was obvious that they needed a perfect Union and so, while protecting the independence of states, the Articles of Confederation didn't describe the powers of a federal chief executive nor a judicial system. The creation of our Constitution and present form of government was informed by these and other considerations that arose during the years of the Confederation.