Separation of Powers

The separation of powers as implemented in the United States is managed by a system of "checks and balances." This system establishes powers as well as limitations for each branch of the U.S. government—executive, legislative, and judicial. The design of the system prevents one branch from becoming more powerful than the others.

The separation of powers is an old concept with roots dating back to the philosophies developed during the Age of Enlightenment (c. 17th–18th centuries) in Europe. The phrase itself was coined by French political philosopher Montesquieu (1689–1755), who was inspired by the ways that the Roman Republic (509–27 b.c.e.) and the Kingdom of Great Britain were governed.

In Montesquieu's philosophy, the "separation" of powers meant a "distribution" of powers across three branches of government—the legislative, executive, and judiciary. Although these branches each had their own roles to play, they were limited by the functions of the other branches. Within such a system, the government's power was decentralized, meaning that no one person or group could have complete control.

America's founders were inspired by Montesquieu's ideas when they crafted the U.S. Constitution in 1787. The Constitution formally instituted the separation of powers model in the United States. Article 1 of the Constitution established the legislative branch, which is responsible for creating laws, among its powers. The legislative branch is further divided into the U.S. House of Representatives and the U.S. Senate. Article 2 provided for the executive branch, which carries out the laws. Finally, Article 3 predicated the judiciary, which is tasked with interpreting the law.

These three branches operate on a system of checks and balances, meaning that each branch of government has individual, separate powers that prevent any one branch from assuming too much control. For instance, although the legislative branch can create laws, the executive branch can veto them. In addition, the judiciary can interpret these laws through the guidelines set forth in the Constitution.

The checks and balances system also gives each branch the power to appoint and impeach members of the other branches. For example, the legislative branch can bring charges of impeachment against the president, who holds the highest office in the executive branch. Other such areas are also governed by the checks and balances system. For instance, the executive branch appoints Supreme Court justices, but they have to be approved by the legislative branch. And although the executive branch can veto a bill, the legislative branch can override that veto with enough votes. The executive branch also commands the military, however, only the legislative branch has the authority to declare war. As such, the checks and balances system extends beyond the creation of laws to maintain a balance among the people working in each branch.

The U.S. Constitution does not state that one branch is more powerful than the others. Much of the power among the three branches seems to be concentrated between the executive and legislative branches. The judiciary is sometimes seen as the weakest of the three. Its only check against the other two branches—judicial review—is not explicitly granted by the Constitution. Yet judicial review can strike down laws based on their constitutionality. Over the years, the U.S. Supreme Court has made increasing use of judicial review.

The separation of powers in the United States and its system of checks and balances contributes to a unique political structure. The large number of interest groups participating in U.S. politics has been attributed to the separation of powers.

During the 18th century, not all states observed the separation of powers in the same manner. The powers of the three branches were sometimes combined or exercised under a single office. Some states, most notably those in the South, favored the strict implementation of the separation of powers model.

Controversies have arisen during the 20th and 21st centuries, especially over the implementation of the separation of powers in the United States. Debates have occurred about the role of the judiciary branch within this system. Some argue that the judiciary relies on the other two branches to function. Others claim that the judiciary functions independently of the other two branches and should not receive interference from them.

Throughout American history, there have been a few instances of the judiciary being exploited to increase the powers of the other branches. One case entailed a "court packing" plan attempted by President Franklin D. Roosevelt (1882–1945) to appoint more judges who were sympathetic to his policies. The legislative branch later struck down this attempt, arguing that it undermined the powers of the judiciary.

Another case of "court packing" occurred during the presidential administrations of Barack Obama (1961–present) and Donald Trump (1946–present), except this time, it was the legislative branch that attempted to pack the court, and it succeeded. While Obama was president, various judicial positions became vacant, including a position on the U.S. Supreme Court upon the death of Justice Antonin Scalia (1936–2016) in early 2016. Although Obama quickly made a nomination, the Republican-led Senate blocked the confirmation process, stating that it was too close to the next election and that the position should be filled by the next administration, slated to transfer into power in January 2017, some 10 months later. The Senate also refused to fill vacancies in the lower courts. Once Trump assumed the presidency, the Senate quickly installed a Republican-leaning justices, packing the courts. In September 2020, another vacancy occurred in the U.S. Supreme Court upon the death of Associate Justice Ruth Bader Ginsberg (1933–2020). Although it was only a four-month span until the next administration took office, the Republican-led Senate confirmed Amy Coney Barrett (1972–present); her swearing in ceremony occurred on October 27, 2020, just days before the U.S. presidential election, which Trump lost.

Tensions between the various branches of government continue to mount when political issues emerge. For example, early in his administration, Trump ordered an immigration ban, which was temporarily halted by the U.S. Supreme Court. This led to friction between the executive and judiciary branches, as Trump perceived the court's actions as an overreach of its powers. In another example, some in the legislature took issue with the judiciary branch when in May 2022 the U.S. Supreme Court upheld a Mississippi law that banned abortions after 15 weeks and overturned the Roe v. Wade ruling from 1973. The decision removed a woman's constitutional right to have an abortion—a right they had held for 50 years. The U.S. House of Representatives, which is part of the legislative branch, moved quickly to codify reproductive rights laws at the federal level to counteract the decision of the Supreme Court. However, the move was blocked by the Senate.