The federal government is split into three branches, and each has a distinct job. Congress, the legislative branch, writes the laws. The President, who leads the executive branch, carries them out. The federal courts, the judicial branch, interpret them and decide whether they square with the Constitution. Understanding the three branches of government and their functions is really a matter of seeing how those three jobs — lawmaking, enforcement, and interpretation — are kept in separate hands on purpose.
Articles I, II, and III of the Constitution set up each branch in that order. The framers wanted no single person or body holding all the levers, so they built a system where the branches have to work with, and against, one another.
The Legislative Branch: Congress Writes the Laws
Article I places all federal lawmaking power in Congress, which has two chambers: the Senate and the House of Representatives.1Constitution Annotated. Article I Legislative Branch The House has 435 voting members serving two-year terms. The Senate has 100 members, two from each state, serving staggered six-year terms so roughly a third of the Senate is up for election every two years.2USAGov. Congressional Elections and Midterm Elections
Article I, Section 8 spells out what Congress can do. It can regulate commerce among the states and with foreign nations, declare war, raise and fund the military, coin money, establish post offices, and create federal courts below the Supreme Court.3Constitution Annotated. Article I Section 8
Congress also controls federal money. Under the Appropriations Clause, no funds can be drawn from the Treasury unless Congress has authorized the spending by law.4Constitution Annotated. Article I Section 9 Clause 7 This is often called the power of the purse. Any bill that raises revenue has to start in the House rather than the Senate, under the Origination Clause.5Constitution Annotated. Article I Section 7 Clause 1 – Origination Clause
Lawmaking is not the whole job. Congress conducts oversight of the executive branch, holds investigative hearings, and controls impeachment. The House has the sole power to impeach a federal official; the Senate has the sole power to try the case.6Constitution Annotated. U.S. Constitution – Article I Because every House seat and roughly a third of Senate seats face voters every two years, Congress is the branch most directly answerable to the public.
The Executive Branch: The President Carries Out the Laws
Article II vests executive power in a single President, whose core duty is to take care that the laws are faithfully executed. The 22nd Amendment caps any one person at two elected terms.7Constitution Annotated. U.S. Constitution – Twenty-Second Amendment
What the President Does
The President is Commander in Chief of the armed forces and directs military operations and national defense.8Constitution Annotated. Presidential Power and Commander in Chief Clause The President negotiates treaties with foreign nations, though any treaty needs approval from two-thirds of the Senate to take effect. That same advice-and-consent process applies to nominations for Supreme Court justices, other federal judges, ambassadors, and senior officials.9Constitution Annotated. Overview of Appointments Clause The House plays no role in confirmations.
On legislation, the President can sign a bill into law or veto it. A vetoed bill dies unless both the House and Senate override with a two-thirds vote in each chamber.10Constitution Annotated. Article I Section 7 Clause 2 – Presentment Clause The President also issues executive orders directing how federal agencies do their work. No single clause explicitly authorizes those orders; their legal footing rests on the President’s broad Article II authority over the executive branch.
Article II also grants a pardon power for federal crimes. It is nearly unlimited, with two significant exceptions: the President cannot pardon a state crime, and cannot use a pardon to undo an impeachment.
The Cabinet and the Agencies
The President runs the executive branch through a Cabinet consisting of the Vice President and the heads of 15 executive departments, including the Departments of Justice, Treasury, and Defense.11Cybersecurity and Infrastructure Security Agency. Federal Civilian Executive Branch Agencies List Most department heads carry the title Secretary. The President nominates them; the Senate confirms them. They run the day-to-day operations of federal government, from tax collection and law enforcement to national parks and public health.
If the President dies, resigns, or cannot serve, the Vice President takes over. After the Vice President, the Presidential Succession Act of 1947 sets a line that continues through the Speaker of the House, the President Pro Tempore of the Senate, and then each Cabinet secretary in the order their department was created.12USAGov. Order of Presidential Succession
The Judicial Branch: The Courts Interpret the Laws
Article III creates the federal courts and gives them the power to decide cases arising under the Constitution, federal laws, and treaties.13Cornell Law Institute. U.S. Constitution Article III At the top is the Supreme Court, which has the final word on what the Constitution means. Below it, Congress has established 13 U.S. Courts of Appeals, organized by geographic circuit and subject matter, and 94 U.S. District Courts, the trial-level courts where most federal cases begin.14United States Courts. Court Role and Structure
Lifetime Tenure
Federal judges appointed under Article III hold their positions “during good behavior,” which in practice means a lifetime appointment with no mandatory retirement age.15United States Courts. Types of Federal Judges The only way to remove one is impeachment by the House and conviction by the Senate. The point of that structure is to insulate judges from political pressure so they can rule on the law rather than on whoever is currently in power.
Judicial Review
The Constitution does not explicitly say courts can strike down laws, but the Supreme Court claimed that authority in 1803 in Marbury v. Madison. Chief Justice John Marshall reasoned that because the Constitution is the supreme law, any ordinary statute conflicting with it must be invalid, and courts are the ones who decide when that conflict exists.16Constitution Annotated. Marbury v. Madison and Judicial Review Judicial review is the judiciary’s most consequential tool. A single Supreme Court decision can invalidate an act of Congress or a presidential action, which is significant authority for an unelected branch.
How the Three Branches Check Each Other
Three separate branches only matter because each can restrain the other two. The Constitution builds in overlapping powers so the branches have to negotiate rather than operate in isolation.
- The President can veto legislation. Congress can override the veto with a two-thirds vote in each chamber, a bar rarely cleared.10Constitution Annotated. Article I Section 7 Clause 2 – Presentment Clause
- Congress controls the federal budget, confirms presidential appointments and treaties through the Senate, and holds the power to impeach and remove the President. The House brings charges; the Senate tries them, and conviction requires a two-thirds vote.17Cornell Law Institute. Overview of Impeachment Trials
- Federal courts can strike down laws passed by Congress or actions taken by the President if they violate the Constitution.16Constitution Annotated. Marbury v. Madison and Judicial Review
- The President and Senate together decide who becomes a federal judge. The President nominates; the Senate confirms or rejects.9Constitution Annotated. Overview of Appointments Clause
- Congress controls the structure and budget of the lower federal courts and can impeach federal judges.
The result is deliberate friction. Passing a major policy change usually requires agreement across branches, which slows things down but makes it harder for one faction to seize control. What some see as gridlock, the framers saw as the design working.
What the Three Branches Do Not Cover: State Government
The three-branch structure described here applies to the federal government. Every state has its own legislature, governor, and court system running in parallel, and most of daily life sits closer to state authority than federal.
The Tenth Amendment states that any power the Constitution does not give to the federal government, and does not specifically deny to the states, belongs to the states or the people.18Constitution Annotated. U.S. Constitution – Tenth Amendment That is why states run their own criminal justice systems, set their own speed limits, and regulate most everyday matters like marriage, property, and local business. The federal government is limited to the powers the Constitution actually grants it, mainly through the list in Article I, Section 8.
When federal and state law do conflict, the Supremacy Clause in Article VI settles the question: the Constitution and federal laws made under it are “the supreme Law of the Land,” and state judges are bound by them regardless of anything in state law to the contrary.19Constitution Annotated. U.S. Constitution – Article VI Congress can override state rules within areas where it has constitutional authority, but it cannot regulate anything it likes. Where that line falls is one of the oldest arguments in American politics, and the courts continue to draw it.