Common Law vs. Statutory Law: Where Rules Come From

Learning Objectives

• Distinguish statutory law from common law.
• Explain why both sources matter for everyday legal situations.
• Recognize that the specific mix varies by country.

Core Content

Statutory law is law written and passed by a legislature — a formal, codified rule, like a specific statute setting a contract requirement or a licensing rule. Common law, used in the U.S. and many other countries, is law built up over time through court decisions — when judges resolve disputes, their reasoning becomes precedent that shapes how future, similar disputes get decided, even without a specific written statute covering the exact situation.

In practice, most real-world legal questions involve both: a statute might set a general rule, and court decisions interpret exactly what that statute means in specific, messy real situations. This matters practically because it explains why "the law" isn't always a single clean sentence you can look up — sometimes the real answer depends on how courts have actually applied a rule in similar past cases, not just what a statute literally says.

Worked Example

Question: A new business owner looks up a statute and assumes it fully answers her legal question. Why might that not be the whole picture?

Student: Based on this lesson, court decisions interpreting that statute might add important detail the statute's plain text doesn't spell out.

Guide: Why would that matter for a real, specific situation she's facing?

Student: Because how courts have actually applied the statute in similar cases could reveal exceptions, boundaries, or interpretations that change how it applies to her situation.

Guide: Exactly — which is part of why complex or high-stakes legal questions benefit from professional guidance, not just a quick statute lookup.

Practice Quiz

Question 1. Statutory law is:

A) Law built from court decisions only B) Law written and passed by a legislature C) Unenforceable suggestions D) Only relevant to criminal cases

Question 2. Common law is:

A) Law built up over time through court decisions and precedent B) The same as statutory law C) Only used in one country D) Irrelevant to modern legal systems

Question 3. In practice, most legal questions involve:

A) Only statutes, never court decisions B) Both statutes and how courts have interpreted them C) Neither source D) Only common law, never statutes

Question 4. Why might looking up a statute alone not fully answer a legal question?

A) Statutes are always complete on their own B) Court interpretation can add important detail not in the statute's plain text C) Statutes are never relevant D) This never happens in practice

Answer Key

1. B, 2. A, 3. B, 4. B

Answers and Explanations

1. Statutory law is the formally codified type, created through the legislative process.

2. Common law builds incrementally through judicial precedent rather than a single legislative act.

3. Real-world legal questions typically require understanding both the written rule and how it's actually been applied.

4. Court interpretation often reveals nuance, exceptions, or boundaries that a bare statute doesn't make obvious.

Key Takeaways

• Statutory law comes from legislatures; common law builds from court decisions and precedent.
• Most real legal questions involve both sources working together.
• A statute's plain text doesn't always tell the whole story.
• This is part of why complex legal questions benefit from professional interpretation.