Probable cause

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In United States criminal law, probable cause is the standard by which an officer or agent of the law has the grounds to make an arrest, to conduct a personal or property search, or to obtain a warrant for arrest, etc. when criminal charges are being considered. It is also used to refer to the standard to which a grand jury believes that a crime has been committed. This term comes from the Fourth Amendment of the United States Constitution:

"Probable" in this case may relate to actual statistical probability, or to a general standard of common behavior and customs. The context of the word "probable" here is not exclusive to community standards and does not predate statistics, as some have suggested.^[1]

• 1 Definitions in the United States of America
  • 1.1 Probationers and parolees
  • 1.2 Accident investigation
• 2 Other countries
• 3 Related cases
• 4 Probable cause hearings
• 5 See also
• 6 References
• 7 External links

Definitions in the United States of America

The best-known definition of probable cause is "a reasonable belief that a person has committed a crime".^[2] Another common definition is "a reasonable amount of suspicion, supported by circumstances sufficiently strong to justify a prudent and cautious person's belief that certain facts are probably true".^[3] Notable in this definition is a lack of requirement for public position or public authority of the individual making the recognition, allowing for use of the term by citizens and/or the general public.

In the context of warrants, the Oxford Companion to American Law defines probable cause as "information sufficient to warrant a prudent person's belief that the wanted individual had committed a crime (for an arrest warrant) or that evidence of a crime or contraband would be found in a search (for a search warrant)". "Probable cause" is a stronger standard of evidence than a reasonable suspicion, but weaker than what is required to secure a criminal conviction. Even hearsay can supply probable cause if it is from a reliable source or supported by other evidence, according to the Aguilar–Spinelli test.

Probationers and parolees

In early cases, the Supreme Court held that when a person is on probation, the standard required for a search to be lawful is lowered from "probable cause" to "reasonable grounds"^[4] or "reasonable suspicion." Specifically, the degree of individualized suspicion required of a search was a determination of when there is a sufficiently high probability that criminal conduct is occurring to make the intrusion on the individual's privacy interest reasonable. The U.S. Supreme held that "[a]lthough the Fourth Amendment ordinarily requires the degree of probability embodied in the term 'probable cause,' a lesser degree satisfies the Constitution when the balance of governmental and private interests makes such a standard reasonable...When an officer has reasonable suspicion that a probationer subject to a search condition is engaged in criminal activity, there is enough likelihood that criminal conduct is occurring that an intrusion on the probationer's significantly diminished privacy interests is reasonable."^[5]

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