The Constitution of the United States is the instrument by which “We the People” created a new national government. One of our great fears as a people, however, was that the authority of this new government might be abused by those who would handle the reins of power. The Founders therefore sought to structure the national government in such a way that no one person or group would be able to exercise too much authority. To this end, the Constitution apportions or divides the powers of the national government among three different branches—the legislative (Congress), the executive (the President and those appointed to assist him or her), and the judicial (the federal courts). This is the principle of separation of powers.
Separation of powers issues arise when it is claimed that one branch of government has usurped or encroached upon the functions of another branch. For example, if the President were to initiate a war without the approval of Congress, the executive’s unilateral action might be challenged on separation of powers grounds since Article I, §8 states that the power to declare war belongs to Congress. A separation of powers argument would also arise if Congress sought to bar the President from entering into treaty negotiations without the prior consent of Congress, for such a requirement would encroach upon the executive’s authority to conduct foreign affairs. In this chapter we examine a number of the principal areas in which separation of powers issues have arisen.
While the doctrine of separation of powers protects each branch of the government against unwarranted encroachment by the other branches, these limitations exist not for the benefit of each branch as such, but as a means of safeguarding the rights of individuals. Boumediene v. Bush, 553 U.S. 723, 742 (2008) (separation of powers “serves … to secure individual liberty”). When separation of powers comes up in court, the principle is more often being invoked by individuals than by the injured federal branch. Bond v. United States, 131 S. Ct. 2355, 2365 (2011) (“[i]n the precedents of this Court, the claims of individuals—not of Government departments—have been the principal source of judicial decisions concerning separation of powers and checks and balances.”). Separation of powers violations therefore cannot be waived by the branch whose powers may have been impaired. For this reason, when the judiciary reviews a law challenged on separation of powers grounds, it is irrelevant that the branch whose authority has been usurped may have consented to the intrusion. “The Constitution’s division of power among the three Branches is violated where one Branch invades the territory of another, whether or not the encroached-upon Branch approves the encroachment.” New York v. United States, 505 U.S. 144, 182 (1992). See, e.g., Immigration and Naturalization Service v. Chadha, 462 U.S. 919 (1983) (invalidating, on separation of powers grounds, legislative veto provision impairing President’s role in lawmaking process, even though statute containing veto provision had been signed by President); Myers v. United States, 272 U.S. 52 (1926) (invalidating, on separation of powers grounds, statute limiting President’s power to fire postmaster, even though statute had been signed by President).