How much information do police officers need to establish that “probable cause” for a search warrant exists?
The Fourth Amendment doesn’t define “probable cause.” Its meaning remains fuzzy. What is clear is that after 200 years of court interpretations, the affidavits submitted by police officers to judges have to identify objectively suspicious activities rather than simply recite the officer’s subjective beliefs. The affidavits also have to establish more than a “suspicion” that criminal activity is afoot, but do not have to show “proof beyond a reasonable doubt.” The information in the affidavit need not be in a form that would make it admissible at trial. (For example, a judge or magistrate may consider hearsay that seems reliable.) However, the circumstances set forth in an affidavit as a whole should demonstrate the reliability of the information. (Illinois v. Gates, U.S. Sup. Ct. 1983.) In general, when deciding whether to issue a search warrant, a judicial officer will likely consider information in an affidavit reliable if it comes from any of these sources: • a confidential police i
