The FOURTH AMENDMENT guarantees in part that "The right of the people to be secure in their persons, houses, papers and effects, against UNREASONABLE SEARCHES and seizures shall not be violated, and no warrants shall issue but upon probable cause.?" The determination of probable cause necessarily turns on specific facts and often requires the courts and the police to make most difficult decisions. The
need for probable cause in American CRIMINAL PROCEDURE arises in three instances: probable cause to ARREST or detain, probable cause to search, and probable cause to prosecute. The first two derive constitutional status directly from the Fourth Amendment and govern the conduct of the police. An inquiry by a judge or GRAND JURY into probable cause for prosecution is not constitutionally required in state cases; however, this check on the exercise of prosecutorial discretion is prescribed by statute or state constitutional mandate in most states and is constitutionally required by the Fifth Amendment in federal cases.
As to arrest and search, the language of the Fourth Amendment does not distinguish between SEARCHES AND SEIZURES of objects, and arrests?"seizures" of the person. While one might assume that the term would have equivalent meanings in both the search and arrest contexts, the differences between arrests of suspects and searches for evidence or contraband require the probable cause standard to be applied to different types of data for the two procedures. Probable cause for a search does not automatically support an arrest, nor does a valid ARREST WARRANT necessarily support a search.
Probable cause in the arrest context was defined by the United States Supreme Court in Beck v. Ohio (1964) as turning on "whether at that moment [of arrest] the facts and circumstances within [the officers'] knowledge and of which they [have] reasonably trustworthy information [are] sufficient to warrant a prudent man in believing that the [suspect] had committed or was committing an offense. There are two potential sources of information?personal knowledge and "trustworthy" secondary data. The Supreme Court has clearly established that secondary data?information not within the officer's personal knowledge?can supply sufficient grounds for an arrest. Thus, the police may rely on reports from other cities or states to support valid arrests, as in Whitely v. Warden (1971). Credible information supplied by an informant may also be used.
The officer's specific knowledge derived from direct contact with the arrestee is usually the primary support for a finding of probable cause. It is clear such information must be specific. Mere knowledge that, for example, a suspect has been convicted in the past coupled with an unidentified INFORMANT ' STIP alleging current criminal activity has been held to be...