A more thorough explanation:

Case law refers to the body of law that is based on judicial decisions rather than written laws or regulations. It is also known as common law.

When a court makes a decision on a particular legal issue, that decision becomes a precedent for future cases. Other courts can use that precedent to guide their own decisions on similar issues. This creates a body of case law that is specific to each jurisdiction.

For example, if a court in New York makes a decision on a particular issue, other courts in New York will be bound by that decision. However, courts in California may look at that decision as persuasive authority, but they are not bound by it.

Case law is important because it helps to clarify and interpret written laws and regulations. It also provides guidance to judges and lawyers on how to approach legal issues.

One example of case law is the landmark decision in Brown v. Board of Education, which declared segregation in public schools to be unconstitutional. This decision has had a significant impact on civil rights in the United States.

Another example is the case of Roe v. Wade, which established a woman's right to choose to have an abortion. This decision has been the subject of much debate and controversy since it was made in 1973.

These examples illustrate how case law can have a profound impact on society and shape the way we think about important legal issues.