In Adams v. Williams, 407 U.S. 143, (1972), the United States Supreme Court reviewed a case wherein a police officer detained an individual upon acting on an informant's tip.
The Adams court stated the following at 147:
"In reaching this conclusion, we reject respondent's argument that reasonable cause for a stop and frisk can only be based on the officer's personal observation, rather than on information supplied by another person. Informants' tips, like all other clues and evidence coming to a policeman on the scene, may vary greatly in their value and reliability.
One simple rule will not cover every situation. Some tips, completely lacking in indicia of reliability, would either warrant no police response or require further investigation before a forcible stop of a suspect would be authorized. But in some situations-for example, when the victim of a street crime seeks immediate police aid and gives a description of his assailant, or when a credible informant warns of a specific impending crime-the subtleties of the hearsay rule should not thwart an appropriate police response."
In Adams v. Williams , the court explained the concept of probable cause:
"Probable cause to arrest depends 'upon whether, at the moment the arrest was made . . . the facts and circumstances within the arresting officers' knowledge and of which they had reasonably trustworthy information were sufficient to warrant a prudent man in believing that the suspect had committed or was committing an offense.' Beck v. Ohio, 379 U.S. 89, 91 (1964)."