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Probable Cause
Probable cause means a police officer has enough trustworthy facts to believe a crime occurred or that evidence is in a specific place, more than a hunch but less than proof.
What it actually is
It is a legal standard under the Fourth Amendment that requires a reasonable basis, based on specific facts, for a search or arrest. It appears when police seek a warrant, make a warrantless arrest, or conduct a vehicle search, and must be judged by what a reasonable officer would have believed under the circumstances.
Why it matters in your case
If a search or arrest lacks probable cause, any evidence obtained may be suppressed and cannot be used against you in court. It also determines whether you can be legally detained before trial—without it, an arrest or seizure may be unlawful.
The common misunderstanding
Many people confuse probable cause with 'reasonable suspicion,' which is a lower standard for brief stops; probable cause requires stronger, more concrete evidence. Another common error is thinking probable cause means guilt—it is only a belief that a crime likely occurred, not a guilty verdict.
Get the actual rule
Definitions are orientation; rules are authority
This page explains the concept. When it matters to your case, read the rule that governs it in your court — we hold Texas, federal and Washington court rules word for word, and every state's official resources are on the state pages. If someone cites a case at you, check that it exists first.
Related
Terms that travel with this one
General explanation, not legal advice, and not specific to any state — procedures and deadlines vary by jurisdiction and court. If you can get a lawyer or free legal aid, do: every real option.