The Constitution contains no provision expliciting declaring that the powers of the three branches of the federal government shall be separated.
James Madison, in his original draft of what would become the Bill of Rights, included a proposed amendment that would make the separation of powers explicit, but his proposal was rejected, largely because his fellow members of Congress thought the separation of powers principle to be implicit in the structure of government under the Constitution. Madison's proposed amendment, they concluded, would be a redundancy.
The first article of the Constitution says "ALL legislative powers...shall be vested in a Congress." The second article vests "the executive power...in a President." The third article places the "judicial power of the United States in one Supreme Court" and "in such inferior Courts as the Congress...may establish."
Separation of powers serves several goals. Separation prevents concentration of power (seen as the root of tyranny) and provides each branch with weapons to fight off encroachment by the other two branches. As James Madison argued in the Federalist Papers (No. 51), "Ambition must be made to counteract ambition." Clearly, our system of separated powers is not designed to maximize efficiency; it is designed to maximize freedom.
http://www.law.umkc.edu/faculty/projects/ftrials/conlaw/separationofpowers.htm
Equality of the branches
The Constitution does not explicitly indicate the pre-eminence of any particular branch of government. One may accurately claim that the judiciary has historically been the weakest of the three branches. Its power to exercise judicial review—its sole meaningful check on the other two branches—was itself doubted by many. In fact, the Court exercised its power to strike down an unconstitutional Act of Congress only twice prior to the Civil War: in Marbury v. Madison (1803) and Scott v. Sandford (1857). While the Supreme Court has since then made more extensive use of judicial review, it cannot be said to have as much political power as either Congress or the President.
http://www.answers.com/topic/separation-of-powers-under-the-united-states-constitution
James Madison, in his original draft of what would become the Bill of Rights, included a proposed amendment that would make the separation of powers explicit, but his proposal was rejected, largely because his fellow members of Congress thought the separation of powers principle to be implicit in the structure of government under the Constitution. Madison's proposed amendment, they concluded, would be a redundancy.
The first article of the Constitution says "ALL legislative powers...shall be vested in a Congress." The second article vests "the executive power...in a President." The third article places the "judicial power of the United States in one Supreme Court" and "in such inferior Courts as the Congress...may establish."
Separation of powers serves several goals. Separation prevents concentration of power (seen as the root of tyranny) and provides each branch with weapons to fight off encroachment by the other two branches. As James Madison argued in the Federalist Papers (No. 51), "Ambition must be made to counteract ambition." Clearly, our system of separated powers is not designed to maximize efficiency; it is designed to maximize freedom.
http://www.law.umkc.edu/faculty/projects/ftrials/conlaw/separationofpowers.htm
Equality of the branches
The Constitution does not explicitly indicate the pre-eminence of any particular branch of government. One may accurately claim that the judiciary has historically been the weakest of the three branches. Its power to exercise judicial review—its sole meaningful check on the other two branches—was itself doubted by many. In fact, the Court exercised its power to strike down an unconstitutional Act of Congress only twice prior to the Civil War: in Marbury v. Madison (1803) and Scott v. Sandford (1857). While the Supreme Court has since then made more extensive use of judicial review, it cannot be said to have as much political power as either Congress or the President.
http://www.answers.com/topic/separation-of-powers-under-the-united-states-constitution