No doubt, the old saying is true: The US is a nation of laws. There are federal laws covering everything from income taxes to discrimination in employment. Every state has laws on crime and punishment, education requirements for children and hundreds of other things that touch our everyday lives. Most counties, cities and towns have laws, too.

With all these laws covering so many things, it's no surprise people disagree over what some laws mean, how they're supposed to work and who exactly they apply to. This is where case law comes into play in the US legal system.

Case Law Explained

The best description of case law is the simplest: It's the rules of law made by courts when interpreting other laws and court decisions when deciding a particular case. It's very different from the other laws you may be familiar with:

  • Statutes  are laws passed by legislatures, such as the US Congress or your state lawmakers
  • Regulations are rules passed by agencies or legislatures that explain how particular laws are supposed to work
  • Constitutions set out our rights and liberties as citizens of the US and our states, as well as outline governments' structures and duties. They're passed by the people and the legislatures

In the US, case law is often called common law. It's not a entirely accurate to use the two terms interchangeably, though. That's because common law also refers to British laws that were passed down or accepted by the Colonies. Of course, there were no US courts interpreting those laws at the time, but some of those common laws are interpreted by the courts today.

An Example Makes It Clear

An example of when and how case law comes about should clear away any confusion.

Say State A passes a law where same-sex marriages aren't recognized. Citizens 1 and 2, who are same-sex partners, are denied a marriage license and file a lawsuit. They claim the law violates their federal and state constitutional rights. The judge agrees with the Citizens and decides that the same-sex marriage ban is legally no good.

The judge's decision is case law.

Case Law Is Law

As a general rule, case law is just as powerful and binding. You or your attorney can use and rely on a court's decision when you have a similar case or legal problem. This is called legal precedent.

For example, in the same-sex example, another couple in State A may use the court's decision to persuade another court in that state that the law is invalid.

Stare Decisis: Courts Follow Other Courts - Sometimes

Stare decisis is where courts honor to other courts' decisions on particular matters. Usually, this involves lower courts making decisions consistent with decisions of higher courts in the same jurisdiction or area. When and if the highest court in jurisdiction weighs in and makes a decision, the rule of law is settled.

Courts in other jurisdictions don't have to follow court decisions from other states or jurisdictions, but they can follow them if they want to.

The US Supreme Court Has the Last Word

The US Supreme Court is the highest authority in many legal battles. Its decisions on the meaning and interpretation of federal laws, regulations and the US Constitution are binding and must be followed by all federal courts. Also, many state courts must follow the Supreme Court's decisions. That's because many state laws impact rights and privileges protected by federal laws and the US Constitution.

So, if the US Supreme Court decides that State A's same sex marriage ban is illegal because it violates the US Constitution, State A - and probably every other state - would be barred from passing a same-sex marriage ban.

Solving practically any legal problem requires knowing more than the statute or regulation involved in the case. You need to know how the courts in your area, and maybe even some federal courts, treat the statute or regulation. Very often it's the key to winning the case.

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