Probable cause may be determined by a magistrate who issues a search or arrest warrant. A warrant may be issued by a magistrate who is not a lawyer, as long as the magistrate is independent of the police and prosecutor. In the alternative, when police are not able to obtain a warrant because of exigent circumstances, a determination of probable cause will be made by a magistrate after the search or seizure.
Probable cause is measured by a totality of the circumstances and does not require proof as high as a preponderance of the evidence. Probable cause to believe that a person has committed a crime is needed for an arrest; probable cause to believe that evidence of a particular crime is located in a particular place is needed for a search.
The identity of a confidential informant does not have to be disclosed to a defendant who contests probable cause. When information from an informant is the basis for some or all of the evidence of probable cause, a court will inquire as to the veracity of the informant and the basis for his or conclusion that criminal activity is occurring.
1. Anonymous Informants
If an informant is anonymous, a substitute for unknown veracity may be corroborations of an informant’s predictions, and a substitute for basis may be self-verifying detail in a tip that refers to the future actions of third parties not readily predicted except by an informant privy to inside information.
a. Standard of Review
An appellate court should review a probable cause finding de novo.