Court cases dealing with the police use of informants have focused on criteria for determining whether or not informant information is sufficient to establish probable cause as a basis for issuing a search or arrest warrant. The 1983 U.S. Supreme Court decision in Illinois v. Gates has had a profound impact on the use of informants. The Court ruled that the standard to be used in determining the existence of probable cause is the totality of circumstances. This apparently eliminates the standard of informant credibility set in Aguilar v. Texas. Since protecting an informant's identity is crucial to the continued effectiveness of this investigative method, it is important that police use them in such a way as to ensure their anonymity. The Supreme Court has ruled that if informants only provide information that establishes probable cause, their identity need not be disclosed in any subsequent legal proceedings. For informants to be used effectively, police investigators must understand their motives and use them accordingly. To deal with potential problems in the use of informants, police departments should develop a policy for their use. This article presents a written policy on informant use that conforms with the recommendations of the Commission on Accreditation for Law Enforcement Agencies. Nineteen references are listed.