Legal glossary

Probable cause

Probable cause: A reasonable basis, based on facts and circumstances, to believe that a crime was committed or that evidence will be found in a particular place. The Fourth Amendment requires probable cause for warrants.

Probable cause — an educator on a video call

What probable cause means

Put simply, probable cause is part of the working vocabulary of a civil case. The short definition above covers the usual meaning. Still, a specific rule, statute or contract can give it a narrower meaning. For that reason, check how it is used in your own documents.

Where probable cause comes up

The term is used across many kinds of cases. For example, you may see it in pleadings, motions and court orders. To see it in context, browse the motions and procedures library or the Learn the Law topics.

How to research the term

To research probable cause, begin with the rule, statute or contract where the word is used. Each one can give it a slightly different meaning. Then compare that text with how courts in your area have applied it. Also check the local rules of your court, since they can add requirements. If your case is in state court, the state rules control. So start with our state procedures guide to find them. In the end, always confirm that the source you rely on is current.

You can read the current federal court rules online for free.

Related legal terms

Why precise terms matter

Legal words often look like everyday words, but they can carry a precise meaning. Because of that, a small misreading can change how you understand a deadline, a duty or a right. Our glossary keeps each definition short and links it to the procedures where it matters.

Sources

Sources last reviewed: 2026-10-24

Lawtopolis provides legal information and education, not legal advice. Using this site does not create an attorney-client relationship. Laws and court rules vary by jurisdiction and change over time; verify every authority against the official source and consult a licensed attorney in your jurisdiction about your situation.