What is the Constitution? The US rulebook in plain words

The Constitution of the United States is the country's supreme law: a document written in 1787 that creates the federal government, divides its power among Congress, the president and the courts, splits power between the nation and the states, and limits what any government may do to the people. It has seven articles and 27 amendments, the first ten of which are the Bill of Rights. Every law and official act must fit inside it.

In short

• The Constitution replaced the weak Articles of Confederation in 1789 with a national government strong enough to tax, regulate trade and act on citizens directly.
• It guards against that strength by separating powers among three branches that check each other, and by leaving many powers to the states.
• It is hard to change on purpose: of nearly 12,000 amendments proposed in Congress, 27 have been ratified.

Why was the Constitution written?

The first plan didn't work. Under the Articles of Confederation, in force from 1781, the United States had a single-house Congress with no power to tax, no power to regulate trade between the states, and no executive or national courts. It could ask the states for money and they could refuse, and they often did. The new country couldn't pay its war debts, states put tariffs on each other's goods, and paper money lost its value.

So delegates met in Philadelphia from 25 May to 17 September 1787. Seventy-four were appointed and 55 attended; Rhode Island sent no one. They had been asked to revise the Articles, and instead wrote a new framework. The hardest fights were over representation, settled by the Great Compromise of a House based on population and a Senate with two seats per state, and over slavery, where the delegates counted three-fifths of enslaved people for seats in the House and barred Congress from ending the slave trade before 1808. Thirty-nine delegates signed on 17 September.

It took effect when nine states ratified. New Hampshire was the ninth, in June 1788, and the new government began in 1789, with George Washington as the first president. Several states agreed only on the understanding that a list of rights would follow.

What does each article say?

The main text is short, around 4,500 words, and opens with a preamble beginning "We the People". Each article has one job.

Article	What it covers, in one line
I	[[what-does-congress-do
II	The president: how the office is filled through electors, its [[what-powers-does-the-president-have
III	The courts: one Supreme Court, lower courts Congress may create, judges serving during good behavior, and treason
IV	The states and each other: honoring each other's records, returning fugitives, admitting new states
V	Amendments: how the Constitution can be changed
VI	Supremacy: the Constitution and federal law beat state law; officials swear to support it; no religious test for office
VII	Ratification: nine states are enough to put it into effect

The way the president is chosen, through electors rather than a direct national vote, is set out in Article II and changed by the 12th Amendment; the note on the Electoral College walks through it.

How does the Constitution limit power?

The framers feared two things at once: a government too weak to govern, which they had just lived through, and one strong enough to become a tyranny. Their answer was to divide power twice.

First, across three branches. Congress writes the laws, the president carries them out, and the courts decide cases under them. Each branch can block the others: the president can veto a bill, Congress can override the veto with two-thirds of both houses, the Senate confirms judges and treaties, Congress can impeach and remove officials, and the courts can strike down laws that break the Constitution, a power the Supreme Court claimed in 1803. These are the checks and balances.

Second, between the nation and the states, called federalism. The federal government has only the powers the Constitution grants it, listed mainly in Article I, Section 8. The 10th Amendment says the rest stay with the states or the people. That is why states run most criminal law, schools, marriage and elections, and why the same act can be legal in one state and not the next.

How is the Constitution amended?

Article V sets two steps, each requiring far more than a majority. To propose an amendment, two-thirds of both the House and the Senate must vote for it; there is also a second route, a national convention called at the request of two-thirds of the states, which has never been used. To ratify, three-fourths of the states must approve.

With today's numbers, that means:

Step	What it takes now
Propose, in the House	290 of 435 votes, if all members vote
Propose, in the Senate	67 of 100 votes, if all members vote
Or call a convention	34 of 50 state legislatures
Ratify	38 of 50 states
Block ratification	13 states are enough

The bar shows in the record. About 11,985 amendments were proposed in Congress from 1789 to January 2025, by one count. Only 33 passed Congress, and 27 were ratified. The six that failed include the Equal Rights Amendment and a 1924 amendment on child labor. The quickest, the 26th, which lowered the voting age to 18, took about 100 days in 1971. The slowest, the 27th, on congressional pay, was proposed in 1789 and ratified in 1992.

What are the amendments about?

They come in clusters. The Bill of Rights, ratified on 15 December 1791, protects speech, religion, the press, assembly, the right to bear arms, and the rights of people accused of crimes, among others. Madison drafted it; the states ratified ten of twelve. After the Civil War, three amendments abolished slavery (13th, 1865), made everyone born in the country a citizen with equal protection of the laws (14th, 1868), and barred denying the vote by race (15th, 1870). Later ones widened the vote, to women in 1920 and to 18-year-olds in 1971, set up the income tax and direct election of senators in 1913, and started and ended Prohibition in 1919 and 1933.

Who decides what the Constitution means?

In a dispute, the courts do, and the Supreme Court has the final word unless the Constitution is amended. Much of the text is broad: "due process of law", "unreasonable searches", "cruel and unusual punishments". Applying those words to cases the framers never imagined, from wiretaps to the internet, is most of what constitutional law is.

Still argued

How to read the Constitution is a long-running debate among judges and scholars. Originalists hold that its words should be read as the public understood them when they were adopted, because that keeps judges bound by the law rather than their own views, and leaves change to amendment. Those who favor a living Constitution argue that broad words were meant to be applied to new conditions, that the amendment process is too hard to be the only route to change, and that the original public meaning is often uncertain anyway. Most judges use some of both, and the debate is about weight and method more than an all-or-nothing choice.

The Constitution is one answer to the question every democracy has to settle: how to let a majority govern while stopping it from overriding everyone else.

Check yourself

• Without looking back: what was wrong with the Articles of Confederation, and how did the Constitution fix it?
• What are the two ways the Constitution divides power, and why both?
• How many states does it take to ratify an amendment, and how many to block one?

Sources

• The Constitution of the United States: A Transcription — National Archives
• A More Perfect Union: The Creation of the U.S. Constitution — National Archives
• The Constitution: Amendments 11–27 — National Archives
• The Bill of Rights: A Transcription — National Archives
• List of proposed amendments to the United States Constitution — Wikipedia
• The Constitution — National Constitution Center