(1) The government has a privilege to refuse to give evidence and to prevent any public officer from giving evidence as to communications made by or to such public officer in official confidence when the public interest would suffer by the disclosure.

(2) The privilege may be claimed by the public officer sought to be examined, or by the chief officer of the department of government administering the subject matter which the evidence concerned. The required showing may be made in whole or in part in the form of a written statement. The judge may hear the matter in chambers, but all counsel are entitled to inspect the claim and showing and be heard thereon. The judge may take any protective measure which the interest of the government and the furtherance of justice may require.

(3) If the circumstances of the case indicate a substantial possibility that a claim of privilege would be appropriate but has not been made because of oversight or lack of knowledge, the judge shall give or cause notice to be given to the officer entitled to claim the privilege and shall stay further proceedings a reasonable time to afford opportunity to assert a claim of privilege.

(4) If a claim of privilege is sustained in a proceeding to which the government is a party and it appears that another party is thereby deprived of material evidence, the judge shall make any further orders which the interests of justice require, including striking the testimony of a witness, declaring a mistrial, finding against the government upon an issue as to which the evidence is relevant, or dismissing the action.