What does probable cause mean when police seek an arrest or search warrant?

In the context of criminal law, probable cause refers to a reasonable ground for supposing that a charge is well-founded or that a crime has been committed. It serves as a vital constitutional safeguard, mandated by the Fourth Amendment to protect individuals against unreasonable searches and seizures.123

When police seek a warrant, they must demonstrate probable cause to a judge or magistrate under oath or affirmation.24

• Arrest Warrants: Authorities must show that a criminal offense has likely been committed and that the specific person named in the warrant is probably guilty.5
• Search Warrants: Authorities must provide evidence to satisfy a judge that there is good reason to suspect that specific evidence of a crime will be found at a particular location.4

The requirement for probable cause ensures that law enforcement's power to interfere with individual liberty is subject to judicial oversight. If a warrant is issued without meeting this standard, or if a search is conducted improperly, evidence obtained may be subject to the exclusionary rule and deemed inadmissible in court.543