Common law: Defining what it is and what you need to know

Common law legal systems can trace their roots back many centuries. Indeed, the common law system as we know it started in England during the Middle Ages. Even today, several countries around the world — including the U.S., Canada, India, and Australia — continue to rely heavily on common law when resolving their legal disputes.

Despite the fact that common law legal systems still exist, many people don’t know much about them or how they work. So, let’s start with the basics.

What is common law?

The simplest definition for common law is that it’s a “body of law” based on court decisions rather than codes or statutes. But in reality, common law is often more complicated than that.

At the center of common law is a legal principle known as stare decisis, which is a Latin phrase that roughly means “to stand by things decided.” In practice, stare decisis is just a fancy way of saying that courts and judges need to follow earlier decisions and rulings — otherwise known as caselaw — when dealing with similar cases later.

For example, if a court makes a particular decision based on a specific set of facts, then the court is required to follow that decision if they ever must make a ruling on the same or closely related issue. Likewise, decisions made by higher courts — like a jurisdiction’s supreme court — are typically binding on lower courts in the same jurisdiction.

But is common law the only type of legal system used today? No, it’s not. Indeed, many countries use another system known as civil law.

How is common law different from civil law?

The two main legal systems used today throughout the world are common law systems and civil law systems. What’s the difference? Well, while common law systems rely on caselaw and legal precedent to guide their decisions, civil law systems rely primarily on codes and statutes.

Specifically, the civil law legal system — which originated in mainland Europe — centers around a comprehensive code of statutes that clearly outlines everything from the procedures for handling claims to the punishment for offenses. Simply put, civil law systems have clear rules for how judges need to rule for many specific disputes. Unlike common law systems, civil law court decisions are not binding in other cases, even if the facts are similar.

Does the U.S. use common law or civil law?

There are many countries throughout the world that use common law legal systems, including the United States, which originally based its common law rules on English common law.

In fact, every U.S. state — with the exception of Louisiana — has a common law legal system. Louisiana stands alone as the only civil law state since its system is still based on the French civil code that was in place before the U.S. purchased it in the early 1800s. Similarly, the U.S. territory of Puerto Rico, which was a Spanish colony for hundreds of years, has a civil law system based on the Spanish civil code. But other than that, the U.S. is a common law country.

It is also worth noting that none of the common law systems in the United States are technically pure common law systems. After all, the U.S. and its many common law states have countless codified statutes that courts must take into consideration.

But, regardless of whether a court is using common law or applying a statute, one thing remains constant in U.S. common law legal systems: the principle of stare decisis. Consequently, even if a common law court is interpreting a statute and not applying common law, prior court decisions interpreting that same statute are precedent and therefore binding. This is a very big difference from civil law legal systems in which a judge’s decision interpreting the text of the code are not binding in later cases involving different parties.

Benefits of a common law system

There is no denying that there are pros and cons for both common law and civil law legal systems. But in the case of common law systems, the benefits and advantages include:

  • Stability and consistency. Common law promotes stability and consistency because everyone involved knows that the ultimate outcome will be based on previous caselaw — and not on subjective, personal viewpoints.
  • Efficiency. Given that judges need only follow precedent when making decisions in common law systems, court proceedings can be much shorter, thereby saving everyone time and money.
  • Adaptability to the unforeseen. When lawmakers create statutes and rules, there is simply no way they can predict the countless situations in which courts may need to apply the laws. Indeed, it’s impossible to legislate every possible problem or scenario. But in common law systems, courts can address situations not originally predicted by lawmakers.
  • Flexibility. Common law has also been described as flexible, since it can respond to changes in society. Unlike civil law systems, common law doesn’t require lawmakers to pass changes in statutes and codes, which can take a long time or never happen at all. When it comes to common law, higher courts can — and sometimes do — overrule prior decisions as “bad law” and they don’t need to wait for lawmakers to do it for them.

How do you research common law?

In common law legal systems, the first thing you will often need to look at are earlier court rulings and decisions. After all, if you want to know what may be binding now, you must first know how they’ve handled similar situations in the past. This means you need to search for relevant caselaw, or legal precedent. But what’s the easiest and fastest way to get that done?

In the past, finding on-point caselaw was typically a time-consuming, arduous process, often involving long hours in the law library poring over countless case reporters and practice guides. You simply hoped that you would eventually stumble across that one perfect case — one that the court decided exactly the way you wanted and matched your facts.

As you can imagine, searching for caselaw in this way certainly wasn’t efficient. You are already busy enough; you don’t have the time to waste.

Fortunately, legal technology has made researching caselaw easier and faster than ever before. In fact, today’s legal tech can help you finish many research tasks in mere minutes, when they used to take hours — if not days.

For example, using Westlaw Precision, the most advanced legal research tool available today, you can instantly filter caselaw by fact pattern, motion type, outcome, and so much more — tasks that would have taken considerably longer in the past. Westlaw Precision also helps you know faster when you can trust that a case is still “good law” for an issue you care about.

With these types of legal tech advancements at your fingertips, it’s easier than ever to find cases that not only match your facts and legal issue but are also decided the way you want. In a common law legal system, finding on-point, relevant caselaw is absolutely essential to success.

The content appearing on this website is not intended as, and shall not be relied upon as, legal advice. It is general in nature and may not reflect all recent legal developments. Thomson Reuters is not a law firm and an attorney-client relationship is not formed through your use of this website. You should consult with qualified legal counsel before acting on any content found on this website.

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