Why three branches?
When the United States Constitution was written in 1787, its authors had just fought a war against a king they believed had abused his power. They wanted a strong national government, but not one that could become a tyranny.
Their solution was the separation of powers: dividing the federal government into three branches, each with its own job.
| Branch | Main job | Who | Where |
|---|---|---|---|
| Legislative | makes laws | Congress: Senate and House of Representatives | U.S. Capitol |
| Executive | carries out laws | president, vice president, Cabinet, federal agencies | White House |
| Judicial | interprets laws | Supreme Court and other federal courts | Supreme Court Building |
The legislative branch: Congress
The legislative branch is described first in the Constitution, in Article I. Congress is bicameral, meaning it has two chambers.
| House of Representatives | Senate | |
|---|---|---|
| Members | 435 (by state population) | 100 (two per state) |
| Term | 2 years | 6 years (one-third elected every two years) |
| Minimum age | 25 | 30 |
| Leader | Speaker of the House | vice president (presiding officer); majority leader |
| Special powers | starts tax and spending bills; can impeach officials | approves treaties and presidential appointments; holds impeachment trials |
Congress also declares war, collects taxes, borrows money, regulates trade and approves the federal budget.
The executive branch: the president
The executive branch (Article II) is led by the president, who is both head of state and head of government.
- elected for a four-year term, with a maximum of two terms (22nd Amendment)
- must be at least 35, a natural-born citizen, and a U.S. resident for 14 years
- commander in chief of the armed forces
- signs or vetoes bills
- makes treaties (with Senate approval)
- appoints Cabinet members, ambassadors and federal judges (with Senate approval)
The vice president takes over if the president cannot serve. The Cabinet includes the heads of executive departments such as State, Defense and Treasury. Agencies such as NASA and the Environmental Protection Agency are also part of the executive branch.
The judicial branch: the courts
The judicial branch (Article III) interprets laws and decides cases.
- The Supreme Court is the highest court. It has nine justices, including a Chief Justice.
- Federal judges are nominated by the president, confirmed by the Senate, and serve for life ("during good behavior"), so they can decide cases without political pressure.
- Lower federal courts include district courts and courts of appeals.
Checks and balances
The branches don’t just have separate jobs. Each can limit the others. This system is called checks and balances.
| Branch | Can check… | How |
|---|---|---|
| Legislative | Executive | override a veto with a two-thirds vote in both houses; approve appointments and treaties; control funding; impeach and remove the president |
| Legislative | Judicial | approve or reject judges; impeach judges; propose constitutional amendments |
| Executive | Legislative | veto bills; call special sessions |
| Executive | Judicial | nominate judges; grant pardons |
| Judicial | Legislative | declare laws unconstitutional |
| Judicial | Executive | declare executive actions unconstitutional |
The power of courts to strike down laws is called judicial review. It is not written directly in the Constitution; the Supreme Court established it in Marbury v. Madison (1803).
Checks and balances in action
- Veto and override: Presidents have vetoed thousands of bills; Congress has overridden only a small fraction.
- Impeachment: The House has impeached a few presidents, but the Senate has never voted to remove one.
- Court rulings: In Brown v. Board of Education (1954), the Supreme Court ruled school segregation unconstitutional, overturning earlier decisions and state laws.
Try it yourself
- Make a three-column chart of the branches, with their leaders, jobs and checks.
- Role-play: Congress passes a bill, the president vetoes it, and Congress tries to override it.
- Why do you think federal judges serve for life? List one benefit and one drawback.
- Find out who represents your state in the Senate and your district in the House.
Quick recap
- The U.S. government has legislative, executive and judicial branches.
- Congress makes laws; the president carries them out; the courts interpret them.
- Checks and balances let each branch limit the others.
- The veto, override, impeachment and judicial review are key checks.
- Separation of powers is designed to prevent any one branch from becoming too powerful.