Law
Sources of Law: Hierarchy, Types and 7 Solved Exercises
Sources of law are ranked: constitution, statutes, regulations, case law, custom. See how conflicts are resolved, with clear tables and 7 solved exercises.
Recommended for: Grade 11 · Grade 12
Sources of law are the places where legal rules come from. They are ranked in a hierarchy: the constitution is at the top, followed by statutes, then regulations (delegated legislation), with case law, custom and international law fitting in according to the legal system. If two rules conflict, the higher one wins.
What counts as a source of law
A source of law is any process or document that gives a rule legal force. Lawyers separate:
- formal sources, which have official authority, such as a statute or a court judgment;
- material sources, such as social, economic or political pressures that push a legislator to act.
This guide covers the formal sources. If you want to see how a real constitution is built, read the explanation of the Italian Constitution and its first twelve articles.
The six main sources: overview
| Source | Who creates it | Example |
|---|---|---|
| Constitution | Founding assembly, amended by a special procedure | US Constitution (1787) |
| Statutes (primary legislation) | Legislature | Acts of Congress, Acts of Parliament |
| Delegated legislation | Ministers and agencies, under a statute | Agency regulations, UK statutory instruments |
| Case law (precedent) | Courts | Marbury v. Madison (1803) |
| Custom | Long, consistent practice felt to be binding | Trade usages |
| International law | States and international bodies | Treaties, EU regulations |
The hierarchy of norms
In every system the idea is the same: each rule draws its authority from a higher one.
| Rank | Source | What it means in a conflict |
|---|---|---|
| 1 | Constitution | Overrides every other rule |
| 2 | International and EU law (where it applies) | Can take priority over national statutes |
| 3 | Statutes | Override regulations and custom |
| 4 | Regulations and delegated legislation | Valid only within the statute that authorises them |
| 5 | Custom | Applies only where statutes are silent |
The position of international law is the part that varies the most. In the EU, regulations are directly applicable and prevail over conflicting national statutes. In the US, treaties are part of the supreme law of the land under Article VI, but they stay below the Constitution.
Constitution and statutes
The constitution sets out how the state works and what rights individuals have. Because it is the highest rule, changing it is harder than passing a statute. In the US, an amendment needs a two-thirds vote in both Houses of Congress and ratification by three-fourths of the states (Article V).
A statute is a law passed by the legislature. In the US this means Congress, and in the UK it means the Parliament in Westminster. The UK has no single codified constitution, and its courts have traditionally treated Acts of Parliament as supreme: this is called parliamentary sovereignty. The Human Rights Act 1998 lets UK courts declare a statute incompatible with human rights but does not let them strike it down.
In a federal system, such as the US, federal and state law coexist. When a valid federal statute conflicts with state law, the Supremacy Clause makes federal law prevail. To see how states can be organised, you can also read the summary on forms of state and government.
Delegated legislation
Legislatures cannot regulate every detail, so they give ministers or agencies the power to make detailed rules. The result is delegated or secondary legislation: federal regulations in the US, statutory instruments in the UK, decrees and ordinances in many European countries.
It always has two limits. It must stay within the power the statute gives, otherwise it is ultra vires (beyond the powers) and a court can annul it. And it can never contradict the statute.
Case law and precedent
In common law systems, courts create law through their decisions. The doctrine of stare decisis (“to stand by things decided”) says that a court must follow earlier decisions of higher courts in the same hierarchy when the facts are similar.
| Type of precedent | Source | Effect |
|---|---|---|
| Binding | Higher court in the same hierarchy | The lower court must follow it |
| Persuasive | Court of the same level, a court in another hierarchy, a foreign court | The judge may consider it, but is not obliged to follow it |
In civil law countries, judges are officially bound by statutes and codes, and previous judgments are persuasive. In practice, though, consistent case law carries heavy weight there too.
A famous case is Marbury v. Madison (1803), in which the US Supreme Court established judicial review: the power to declare statutes unconstitutional.
Custom and international law
Custom requires two elements: a practice repeated over time and the belief that it is legally required. In modern systems it is a weak source, and applies when statutes do not cover the subject or when a statute refers to it.
International law comes from treaties and customary rules among states. Whether it applies directly in a country depends on its constitution. EU law is a special case, since EU regulations apply directly in member states and directives must be transposed into national law.
Two legal families compared
| Civil law | Common law | |
|---|---|---|
| Main source | Codes and statutes | Statutes and judicial precedent |
| Role of judges | Apply the code | Interpret and also develop the law |
| Precedent | Persuasive | Binding (stare decisis) |
| Examples | Italy, France, Germany, Spain | UK, US, Canada, Australia |
Most common mistakes
- Treating regulations as equal to statutes. Regulations are lower and valid only inside their statute.
- Saying common law judges “make up” the law. They decide cases within precedent and statutes, not freely.
- Thinking all precedent is binding. Only decisions of higher courts in the same hierarchy bind.
- Applying the “newer law wins” rule across ranks. A newer regulation never beats an older statute.
- Rounding a threshold down. Two thirds of 100 is 67, not 66.
- Confusing federal and state hierarchies. Federal law prevails only in matters within federal powers.
Quick summary
- Sources: constitution, statutes, delegated legislation, case law, custom, international law.
- In conflicts, the higher source prevails; among equals, the newer or more specific rule wins.
- Civil law centres on codes, common law on precedent plus statutes.
- Delegated legislation is valid only within the limits of its statute.
Solved exercises
1. Classify each item as constitution, statute, delegated legislation, case law, custom or international law: a) the Clean Air Act passed by Congress; b) a rule issued by the Environmental Protection Agency under that Act; c) the decision in Marbury v. Madison; d) the First Amendment; e) a treaty signed by the United States; f) a trade practice followed for decades. base
Show solution
- a) A law passed by a legislature is a statute (primary legislation).
- b) A rule made by an agency under power given by a statute is delegated (secondary) legislation, often called a regulation.
- c) A court decision that creates a rule is case law, also called precedent.
- d) The First Amendment is part of the US Constitution, so it is constitutional law.
- e) A treaty is international law. Under Article VI of the US Constitution, treaties made under US authority are part of the supreme law of the land.
- f) A practice followed for a long time and felt to be binding is custom.
Answer: a) statute; b) delegated legislation; c) case law; d) constitution; e) international law; f) custom.
2. True or false? Correct the false statements. a) In civil law countries such as Italy, France and Germany, the main source of law is codified legislation. b) In common law countries, judges never create law. c) A regulation can override the statute it implements. d) International law is always above a country's constitution. base
Show solution
- a) True. Civil law systems rely mainly on codes and statutes, and judges apply them.
- b) False. In common law systems such as the UK and the US, judicial decisions create binding precedent, so judges do shape the law.
- c) False. Delegated legislation gets its power from a statute and is invalid if it goes beyond it (ultra vires).
- d) False. How international law ranks varies from state to state, and in many countries the constitution comes first. In the US, treaties are supreme law but cannot override the Constitution.
Answer: a) True; b) False; c) False; d) False.
3. Decide which rule prevails in each conflict: A) a federal statute and a state statute on the same subject, both within valid powers; B) a statute and the Constitution; C) a regulation and the statute that authorises it; D) two statutes of the same legislature, the older one saying the opposite of the newer. intermedio
Show solution
- A) The Supremacy Clause (Article VI) makes federal law supreme, so the state law yields where there is a real conflict.
- B) The Constitution is the highest law. A court can strike down a statute that contradicts it (judicial review).
- C) The statute prevails. The regulation exists only because the statute allows it, so it cannot go beyond what the statute authorises.
- D) The newer statute prevails over the older one on the same point: this is the later-in-time rule, and the older provision is impliedly repealed.
- Notice that A, B and C use the hierarchy, while D uses time: it applies only between rules of the same rank.
Answer: A) federal statute; B) the Constitution; C) the statute; D) the newer statute.
4. A US federal district court in Ohio must decide a case. Say whether each decision is binding or only persuasive: 1) a ruling of the US Supreme Court; 2) a ruling of the Sixth Circuit Court of Appeals, whose territory includes Ohio; 3) a ruling of the Ninth Circuit, which covers western states; 4) a ruling of another district court in Ohio. intermedio
Show solution
- 1) Binding. Decisions of the Supreme Court bind every lower federal and state court on federal law.
- 2) Binding. The district court sits inside the Sixth Circuit and must follow its appeals court.
- 3) Persuasive only. The Ninth Circuit is a different court of appeals, so the Ohio judge may consider its reasoning but is not required to follow it.
- 4) Persuasive only. A court of the same level does not bind its equals.
- The rule is that precedent binds only courts that are lower in the same hierarchy (stare decisis).
Answer: 1) binding; 2) binding; 3) persuasive; 4) persuasive.
5. Article V of the US Constitution allows an amendment to be proposed by two-thirds of both Houses and ratified by three-fourths of the states. Assuming all members vote, how many votes are needed in the House (435 members) and the Senate (100 members), and how many states must ratify (50 states)? intermedio
Show solution
- House: 435 × 2/3 = 290 exactly, so 290 votes are enough.
- Senate: 100 × 2/3 = 66.67, and votes are whole numbers, so 67 are needed.
- States: 50 × 3/4 = 37.5, so 38 states must ratify.
- Always round up for a threshold: 66 senators would be 66%, below two thirds.
Answer: House: 290; Senate: 67; ratification: 38 states.
6. A bill is vetoed by the President. The House votes 300 to 135 to override, and the Senate votes 66 to 34. Assuming all 435 representatives and 100 senators vote, does the bill become law? Then explain what would change if the Senate voted 67 to 33. avanzato
Show solution
- An override needs two thirds of each House voting.
- House: 435 × 2/3 = 290. Since 300 is at least 290, the House succeeds (300 ÷ 435 ≈ 69%).
- Senate: 100 × 2/3 = 66.67, so 67 votes are required. With 66 the Senate fails, even though 66 is just 1 short.
- Because both Houses must override, the failure in the Senate is enough: the veto stands and the bill does not become law.
- With 67 to 33, both Houses reach the threshold and the bill becomes law despite the veto.
Answer: No: the House passes the override but the Senate falls one vote short (66 < 67). With 67 votes it becomes law.
7. In Marbury v. Madison (1803), William Marbury asked the Supreme Court to order the delivery of a commission, relying on a provision of the Judiciary Act of 1789. Reconstruct the Court's reasoning in steps and say why the case is a source of law. avanzato
Show solution
- Chief Justice John Marshall first found that Marbury had a right to the commission and that the law provided a remedy.
- He then asked whether the Court could issue the order directly. Section 13 of the Judiciary Act of 1789 said yes, giving the Court that power as a court of first instance.
- Article III of the Constitution listed the cases the Supreme Court can hear at first instance, and this was not one of them. The statute thus conflicted with the Constitution.
- Marshall concluded that an ordinary statute that contradicts the Constitution is void, since the Constitution is the higher law.
- Result: Marbury lost on jurisdiction, but the Court established judicial review, the power to strike down unconstitutional laws. The case works as precedent and so counts as case law.
Answer: The Court held that Section 13 conflicted with Article III and was void, so it could not hear Marbury's claim. In doing so it established judicial review, which is why the decision is a major source of constitutional law.
FAQ
What are the main sources of law?
The constitution, statutes (laws passed by a legislature), delegated legislation such as regulations, case law (judicial precedent), custom and international law. Which of these matters most depends on the legal system: statutes dominate in civil law countries, while case law is central in common law countries.
What is the hierarchy of laws?
The usual order is constitution, then statutes, then regulations and other delegated legislation, then custom. A lower rule that contradicts a higher one is invalid. In the EU, directly applicable EU law also takes priority over conflicting national statutes.
What is the difference between civil law and common law?
Civil law systems, such as Italy, France, Germany and Spain, rely mainly on written codes and statutes. Common law systems, such as England and the United States, also rely heavily on judicial precedent: earlier decisions of higher courts bind later cases.
What is the difference between primary and secondary legislation?
Primary legislation is made by a legislature, like an Act of Parliament or a law passed by Congress. Secondary (delegated) legislation is made by a minister or agency under power that a statute gives it, such as a UK statutory instrument or a US agency regulation. It is lower in rank and can be struck down if it exceeds that power.
What is stare decisis?
It is the principle that courts follow earlier decisions on the same legal question. Precedents from higher courts in the same hierarchy are binding. Decisions from courts outside that hierarchy, or at the same level, are only persuasive.