Separation of powers Summary

  • Last updated on November 11, 2022

Also called “checks and balances” or “shared powers,” the system by which the legislative, executive, and judicial branches of the government perform different functions and can restrain the other branches.

The Framers of the U.S. Constitution believed that a system of separation of powers was necessary to protect liberty. Although the idea can be traced to older schemes of mixed government, the delegates to the Constitutional Convention of 1787 were most familiar with Baron Charles de Montesquieu’s Spirit of the Laws (1748). Although Montesquieu’s interpretation of English government, on which the book was based, was later shown to be incomplete, the principle he espoused was adopted at the Constitutional Convention. Separation of powers is woven into the U.S. Constitution in subtle and brilliant ways. Many Supreme Court decisions have operated to preserve and strengthen the system of separation of powers, and the Court is itself one of the major repositories of shared power.

Trial of president Andrew Johnson, whose impeachment trial was a major test of the separation of powers.

(Library of Congress)

The broader structure of the U.S. system helps prevent governmental excess, supplementing formal constitutional separation of powers. The United States has a federal system in which the states retain and exercise significant power. The powers of the central government are listed, and at least in constitutional theory, powers not on the list may not be exercised. Elected officials serve staggered terms and have different constituencies.


In its lawmaking functions, Congress is subject to two immediate constitutional requirements. The first of these is bicameralism. Any bill or resolution that is to have the force of law must be passed by both the Senate and the House of Representatives in identical form. This requirement alone establishes a heavy majoritarian bias, especially given that senators and representatives come from disparate constituencies. The second requirement is presentment. Every bill must be presented to the president of the United States for approval. If he or she signs the bill, it becomes law. If the president fails or refuses to act on it within ten days (Sundays excepted), it becomes a law without his or her signature unless Congress has already adjourned at the end of a session, in which case the bill is said to be “pocket vetoed” and does not become a law. The president may veto a bill by sending it back to Congress with a message giving the reasons for disapproval. In this case, the bill does not become law unless each house of Congress passes it again by a two-thirds vote. Given the usual distribution of party strength in a two-party system, it is rare for vetoes to be overturned. Although President George Bush faced Democratic majorities in both the House and the Senate, the necessary votes to reverse his vetoes could be mustered only once.

One of the most subtle and important limits on the powers of Congress is found in the appointments clause of Article II of the U.S. Constitution. This clause gives the president the power to “nominate and by and with the advice and consent of the Senate…appoint ambassadors, other public ministers and consuls, judges of the Supreme Court, and all other officers of the United States whose appointments are not herein otherwise provided for, and which shall be established by law; but the Congress may by law vest the appointment of such inferior officers as they think proper in the President alone, in the courts of law, or in the heads of departments.” Congress is excluded altogether. Congress may not appoint any person who has executive powers; therefore, it may not establish agencies that compete with the executive branch, which is run by the president. The Court has firmly and consistently reaffirmed this exclusion of Congress from executive power in several cases including Buckley v. Valeo[case]Buckley v. Valeo[Buckley v. Valeo] (1976), which struck down a mixed presidential-congressional appointment scheme for members of the Federal Election Commission. Similarly, in Bowsher v. Synar[case]Bowsher v. Synar[Bowsher v. Synar] (1986), the court struck down a legislative scheme that gave budget-balancing powers to the comptroller-general of the United States. The comptroller-general, being a congressional officer rather than an officer of the United States, cannot exercise executive powers or functions.

Congress may not prevent the president from dismissing executive branch officers. Although Congress has made several attempts to establish this power, it was prevented from doing so by the Court in Myers v. United States[case]Myers v. United States[Myers v. United States] (1926), in which Congress challenged the dismissal of a postmaster by President Woodrow Wilson.

The powers of Congress are also limited by the courts, for every statute must be interpreted when it is applied. Beyond normal judicial processes is the practice of judicial review, which is the process by which the judiciary, especially the Supreme Court, scrutinize laws to see if they are consistent with the Constitution. Although this power of the courts is not explicitly set out in the Constitution, they have exercised it ever since the Court’s decision in Marbury v. Madison[case]Marbury v. Madison[Marbury v. Madison] (1803). In Marbury, the Court held that a section of the Judiciary Act of 1789 was “repugnant” to the Constitution because it seemed to give the Court original jurisdiction beyond the grant of constitutional jurisdiction found in Article III. The Court reasoned that Congress could not change the Constitution by an ordinary legislative act because the Constitution expresses the will of the entire public, and the powers of Congress are given and limited by the Constitution. Moreover, the Constitution itself defines “the supreme law of the land” as “this Constitution and the laws made in pursuance thereof.” A law not in accordance with the Constitution is not part of the supreme law of the land and may not be enforced by the courts. After Marbury, the Court held dozens of federal laws unconstitutional, thus preventing Congress from exceeding its constitutional powers.Judicial review

Executive Branch

Like Congress, the president is limited by the other branches of the government. His official acts are subject to review for constitutionality by the courts, so that if the president or executive officers violate the Constitution or exceed their authority, their actions can be halted.Presidential powers

The Constitution contains a wonderful two-edged phrase to define executive authority: The president is to “take care that the laws be faithfully executed.” He or she is given the power to execute the laws but must do so “faithfully” which is to say in accordance with the will of Congress. The Court, in the landmark case Youngstown Sheet and Tube Co. v. Sawyer[case]Youngstown Sheet and Tube Co. v. Sawyer[Youngstown Sheet and Tube Co. v. Sawyer] (1952), held that President Harry S Truman could not seize the nation’s steel mills in order to avert a national strike in the midst of the KoreanKorean War War. Although President Truman had argued that the sum of the president’s executive and war powers provided constitutional justification for the seizure, the court decided that without statutory authorization, the president did not have this power. Truman released the mills.

Should a president fail to execute the laws faithfully, and if the political will exists, he or she can be impeached by the House of Representatives, tried before the U.S. Senate, and if convicted, removed from office. Two U.S. presidents, Andrew Johnson and Bill Clinton, have been impeached, but neither was convicted.Impeachment of presidents

The ordinary legislative powers of Congress also may serve as powerful check on presidential power. Only Congress may appropriate money for governmental functions, and all federal agencies and bureaus are created by and may be abolished by Congress. Statutory authority given the president may be modified or withdrawn whenever Congress wishes. Most presidential appointments require the consent of the Senate, as do treaties made with foreign powers. The war powers are similarly shared: Although the president is the commander in chief, it is Congress that declares war, raises and supports armies, and makes the rules for the governance of the armed forces. Although the presidency appears to be at the center of the political system, Congress actually lies at the center of the constitutional system. Simply put, Congress can get rid of the president, but not vice versa.


Federal judges serve for life, but they, like the president, may be removed by impeachment if they commit crimes, and Congress has removed four federal judges for such crimes as bribery and tax evasion.Impeachment of judges Judges are appointed by the president with the advice and consent of the Senate; therefore, sitting judges have no control over the ideology of newer judicial appointees. Moreover, the entire judicial structure, except for the Supreme Court itself, is established by Congress and can be reorganized whenever Congress desires. Although the Court is established by the Constitution, Congress sets the size of the Court and may decree the length and frequency of its sittings. In fact, Marbury was delayed for a year because Congress passed a law canceling the Court’s 1802 term. Congress also has the power to make “exceptions” to the appellate jurisdiction of the Court that is, to take away its power to hear certain cases. This power was exercised by Congress when, just after the Civil War, it took from the Court’s jurisdiction certain Reconstruction cases. The Court recognized and accepted this Congressional power in Ex parte McCardle[case]McCardle, Ex parte[MacCardle, Ex parte] (1869).

The greatest limit on the power of the judiciary, however, is the cases and controversiesCases and controversies rule. Courts may decide only issues that come before them in cases. If there is no case, there is no judicial power. Moreover, because prosecution is an executive function, it is the president and the attorney general who decide what cases to bring and what arguments to make. Consequently courts are always responding rather than initiating. For this reason, Alexander Hamilton in The Federalist (1788), No. 78, remarked that the judiciary was “the least dangerous branch” of the government.

Constitutional decisions of the Court can also be reversed by constitutional amendment if there is enough public concern. The Civil War Amendments collectively reverse the Court’s decision in Scott v. Sandford (1857), and the income tax amendment (Sixteenth Amendment) reverses Pollock v. Farmers’ Loan and Trust Co. (1895).

Further Reading
  • There are a number of fine studies of the relationship of the judiciary to the other branches of the federal government. These include Kermit L. Hall’s The Least Dangerous Branch: Separation of Powers and Court-Packing (New York: Garland, 2000), Richard L. Pacelle’s The Role of the Supreme Court in American Politics: The Least Dangerous Branch? (Boulder, Colo.: Westview Press, 2002), Jeffrey Rosen’s The Most Democratic Branch: How the Courts Serve America (New York: Oxford University Press, 2006), Stephen Powers’s The Least Dangerous Branch? Consequences of Judicial Activism (Westport, Conn.: Praeger, 2002), and Institutions of American Democracy: The Judicial Branch, edited by Kermit L. Hall and Kevin T. McGuire (New York: Oxford University Press, 2005). The most powerful arguments for and best general explanations of the U.S. constitutional system are found in The Federalist (1788), a series of essays in support of the proposed Constitution by Alexander Hamilton, James Madison, and John Jay. Nos. 10, 69, and 78 are particularly relevant to understanding the system of separation of powers. Edward S. Corwin’s The Higher Law: Background in American Constitutional Law (Ithaca, N.Y.: Cornell University Press, 1929) explores the theoretical rationale for judicial review, while Nine Men: A Political History of the Supreme Court from 1790 to 1955 by Fred Rodell (New York: Random House, 1955) argues the undemocratic nature of the process. The powerful divergent opinions of Chief Justices William H. Rehnquist and Associate Justice Antonin Scalia in Morrison v. Olson (1988), which involves a challenge to the constitutionality of the Ethics in Government Act of 1978, illuminate the nature of executive power and the appointments clause of the Constitution. The Supreme Court and the Powers of the American Government by Joan Biskupic and Elder Witt (Washington, D.C.: Congressional Quarterly, 1997) shows how the Court has limited federal power. Robert A. Goldwin, an iconoclastic conservative, and Art Kaufman have edited Separation of Powers: Does It Still Work? (Washington, D.C.: American Enterprise Institute for Public Policy Research, 1986), which argues that the system could still work, but it has been abandoned in practice. Some of the practical consequences of separation of powers are discussed in Howard E. Shuman’s Politics and the Budget: The Struggle Between the President and the Congress (Englewood Cliffs, N.J.: Prentice-Hall, 1984).

Appointment and removal power

Congress, arrest and immunity of members of

Constitutional Convention

Executive immunity


Impeachment of judges

Impeachment of presidents

Judicial review

McCardle, Ex parte

Morrison v. Olson

Myers v. United States

Nominations to the Court

Pollock v. Farmers’ Loan and Trust Co.

Presidential powers

Categories: History