(a) Rule of Privilege. The United States or a state or subdivision thereof has a privilege to refuse to disclose the identity of a person who has furnished information relating to or assisting in an investigation of a possible violation of a law to a law enforcement officer or member of a legislative committee or its staff conducting an investigation.
(b) Who May Claim. The privilege may be claimed by an appropriate representative of the public entity to which the information was furnished, except the privilege shall not be allowed in criminal cases if the state objects.
(1) Voluntary disclosure; informer a witness. No privilege exists under this rule if the identity of the informer or the informer’s interest in the subject matter of the communication has been disclosed to those who would have cause to resent the communication by a holder of the privilege or by the informer’s own action, or if the informer appears as a witness for the public entity.
(2) Testimony on merits. If it appears from the evidence in the case or from other showing by a party that an informer may be able to give testimony necessary to a fair determination of a material issue on the merits in a civil case to which the public entity is a party, or on guilt or innocence in a criminal case, and the public entity invokes the privilege, the court shall give the public entity an opportunity to show in camera facts relevant to determining whether the informer can, in fact, supply that testimony. The showing will ordinarily be in the form of affidavits, but the court may direct that testimony be taken if it finds that the matter cannot be resolved satisfactorily upon affidavit. If the court finds that there is a reasonable probability that the informer can give the testimony, and the public entity elects not to disclose the informer’s identity, the court in a civil case may make any order that justice requires, and in a criminal case shall, on motion of the defendant, and may, on the court’s own motion, dismiss the charges as to which the testimony would relate. Evidence submitted to the court shall be sealed and preserved to be made available to the appellate court in the event of an appeal, and the contents shall not otherwise be revealed without consent of the public entity. All counsel and parties shall be permitted to be present at every stage of proceedings under this subdivision except a showing in camera, at which no counsel or party shall be permitted to be present.
(3) Legality of obtaining evidence. If information from an informer is relied upon to establish the legality of the means by which evidence was obtained and the court is not satisfied that the information was received from an informer reasonably believed to be reliable or credible, it may require the identity of the informer to be disclosed. The court shall, on request of the public entity, direct that the disclosure be made in camera. All counsel and parties concerned with the issue of legality shall be permitted to be present at every stage of proceedings under this subdivision except a disclosure in camera, at which no counsel or party shall be permitted to be present. If disclosure of the identity of the informer is made in camera, the record thereof shall be sealed and preserved to be made available to the appellate court in the event of an appeal, and the contents shall not otherwise be revealed without consent of the public entity.