The Legislature is the prime law-making body and it is called the Congress in the United States. It is divided into two houses---The Senate and the House of Representatives. The Congress passes bills and transforms them into acts and laws, approves or disproves of the appointments made by the President, it declares wars and also gives its consent on treaties.
The Executive branch is the one that ensures the execution of laws passed by the Legislature. In the United States, the President is the head of the Executive organ of the Government and performs numerous functions. The most important ones among those functions are, that he is the Commander-in-Chief, he makes appointments in association with the recommendations of the Legislature, he can veto bills and laws; besides ensuring the proper implementations and execution of laws.
The Judiciary is the body of the government that undertakes the job of administering justice and taking charge of the criminal and civil offences in the country. In the United States, the Supreme Court is the apex court, which also serves as the highest court of appeal. The other federal courts exercise their functions in accordance with their position in the hierarchal set-up. The Judiciary also interprets laws for the country. In addition to this, it also performs the functions of Judicial Review, which means, it undertakes the task of declaring a bill/act or law unconstitutional, if it goes against the Constitution of the United States.
The Constitution of the United States also has a system of Checks and Balances, wherein each organ of the Government is granted autonomy, as well as, responsibility. In other words, one organ of the government can check the other organ, in case it goes beyond its sphere of activity or conducts proceedings in a manner that is outside its power. This way, none of the organs can attain supremacy over the other, in spite of maintaining their exclusiveness in their own realm. It, thus, checks and balances the functioning of all the three organs of the Government.
In this process of working together and taking charge of the whole Governmental machinery and functioning, the three organs could sometimes overlap each other in their functioning and cause chaotic situations. The most common possibility of this occurrence is between the Legislature and the Judiciary! Sometimes, it so happens that in the process of interpreting laws that have been made by the Legislature, the Judiciary not only interprets it but also adds its own interpretations and thus, leads to the framing of new laws.
This can prove to be quite confusing and