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What is Case Law?

Case law comprises court rulings that interpret legislation and set legal precedents. These judicial decisions guide future cases, shaping our understanding of laws. Intrigued? Discover how landmark cases have influenced today's legal landscape—continue reading for a visual journey through the annals of case law.
Brendan McGuigan
Brendan McGuigan

Case law is the body of available writings explaining the verdicts in a case. It is most often created by judges in their rulings, when they write their decisions and give the reasoning behind them, as well as citing precedents in other cases and statutes that had a bearing on their decision. A single case may generate virtually no written interpretations or opinions, or, as is the case with many that come before the US Supreme Court, it may generate a number of opinions as it works its way through various lower-circuit courts. These collected opinions can be referred to in the future by other judges when they make their rulings on similar cases, allowing the law to remain relatively consistent.

In the United States, state trial courts, such as the California Circuit Court, do not publish opinions, and so do not generally add to the body of case law. Federal trial courts, such as the U.S. District Court, rarely publish opinions. The bulk of published opinions, available both online and in print form, come from both the state and federal higher courts. Official government agencies publish both federal Supreme Court and state higher court decisions, while the opinions of the US Circuit Courts are published by private agencies.

Case law consists of verdicts made in court cases.
Case law consists of verdicts made in court cases.

Case law is often referred to as common law in many regions of the world and is also known as judge-made law. This latter term derives from the fact that, while legislation is technically passed in most countries by a separate legislative branch, courts are often able to exercise a moderate amount of quasi-legislative power through the use of precedent. Case law is viewed by most people as a crucial part of a functioning judiciary, as it allows for courts to transform decisions that may have taken a great deal of time and energy to arrive at into a sort of de facto law, making future cases much easier to decide.

The United States Supreme Court uses case law when it issues rulings.
The United States Supreme Court uses case law when it issues rulings.

In some cases, a judge may intentionally go against established case law in an effort to begin the process of re-examining a precedent and perhaps ultimately changing it. This often happens with precedents that a judge may consider outdated or irrelevant in the contemporary climate. By issuing a decision that the judge knows will be appealed, he or she pushes the case into higher courts where the old established practices may be overturned in favor of a new outlook.

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Discussion Comments


@matthewc23 - Good question. Opinions are the published decisions of the courts. Like the article says, most lower courts don't publish opinions, but most higher ones do. Basically, the opinion will be written for the majority, dissent, and any concurring opinions. In the US Supreme Court, one judge will be selected to write for the majority and dissent. Concurring opinions are written by anyone who agrees with one of the sides, but for different reasons.

To be honest, unless you are interested in a certain case, reading opinions is going to be pretty boring for most people. If you are interested in law, though, they can be very stimulating. The Supreme Court justices are very intelligent. They didn't get there for nothing, and some of the decisions are very well thought out and convincing. If you're ever would want to read one, they are all posted online.


@Izzy78 - Very good. I wasn't thinking of case law being used like that, but it makes sense.

I am not much on studying law, but we were talking about common law in my civics class today, so I was curious about it. What exactly does the article mean when it talks about "opinions?" I have also heard this term used a lot on TV when the news is talking about the Supreme Court.

I think it is good that case law is used. I don't think it would be good if every court was giving different types of punishments for the same crimes. It seems like eventually you would end up with lots of criminals moving to places that had more lenient judges.


@anon67911 - I guess from my understanding of the article that something like a DUI, theft, or other basic crime could fall under the umbrella of case law depending on how you looked at it.

I believe most case law refers to determining whether a criminal act was even committed in the first place. For example, with the Endangered Species Act how do you determine if a species is endangered? Case law has been established by the Supreme Court to help with that.

With other crimes, though, case law could be applied to the sentencing. Using the DUI example, the law might say that your license is suspended 30 to 90 days. Well, which is it? Using case law, a judge will know what other similar cases have gotten and give you a similar punishment.


@anon11870 - Nearly any ruling by the U.S. Supreme Court could be considered a part of case law. The same could be said for the terminal state courts and even U.S. Circuit courts if the case doesn't move onto the Supreme Court.

The Supreme Court doesn't try every case like the lower courts do. They pick and choose the cases every year that they believe are most important to establishing case law. These usually include cases based on laws that may be outdated, ambiguously worded, or possibly unconstitutional.

Whenever the Supreme Court makes a decision, all other courts and jurisdictions in the U.S. must follow their ruling. At the same time, jurisdictions may use Supreme Court rulings to modify their current statutes, because they are not in compliance with the highest court.


From what I got here, is that case law is the collection of opinions that different judges have used for a similar case and which can be used for reference by other judges?


Wouldn't a DUI be a form of case saw? I can't really see where it fits into any of the amendments. Can anyone help?


In the case of Terry v Ohio, three subjects were frisked for weapons due to suspicious activities. When they were frisked by patting down the outer clothing, the officer felt what he believed to be a weapon in the suspect's jacket, the officer then retrieved the weapon.

The suspect in question appealed his case after being found guilty, which in turn caused this case.

After numerous appeals to go to the supreme court, the supreme court ruled that this type of search was not a violation of the 4th amendment due to the fact that the officer never went into the jacket until he felt the revolver. In other words, the officer did not violate the Fourth Amendment right by an illegal search, and in turn, this became case law.


I need help with Missouri case law for limiting us of private eaaement that is on my deed, The land does not have anyone living on it. It is used for hunting


Does anyone if case law has ever been used in private easement cases?


What is the process by which a law becomes "case law?" does anyone have an example?

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    • Case law consists of verdicts made in court cases.
      By: Andrey Burmakin
      Case law consists of verdicts made in court cases.
    • The United States Supreme Court uses case law when it issues rulings.
      By: Bastos
      The United States Supreme Court uses case law when it issues rulings.