23.—(1) A head may refuse to grant a request under section 7 if access to the record concerned could, in the opinion of the head, reasonably be expected to—

(a) prejudice or impair—

(i) the prevention, detection or investigation of offences, the apprehension or prosecution of offenders or the effectiveness of lawful methods, systems, plans or procedures employed for the purposes of the matters aforesaid,

(ii) the enforcement of, compliance with or administration of any law,

(iii) lawful methods, systems, plans or procedures for ensuring the safety of the public and the safety or security of persons and property,

(iv) the fairness of criminal proceedings in a court or of civil proceedings in a court or other tribunal,

(v) the security of a penal institution,

(vi) the security of the Central Mental Hospital,

(vii) the security of a building or other structure or a vehicle, ship, boat or aircraft,

(viii) the security of any system of communications, whether internal or external, of the Garda Síochána, the Defence Forces, the Revenue Commissioners or a penal institution,

F44[(aa) endanger the life or safety of any person,]

(b) reveal or lead to the revelation of the identity of a person who has given information to a public body in confidence in relation to the enforcement or administration of the civil law or any other source of such information given in confidence, or

(c) facilitate the commission of an offence.

(2) Where a request under section 7 relates to a record to which subsection (1) applies, or would, if the record existed, apply, and the head concerned is satisfied that the disclosure of the existence or non-existence of the record would have an effect specified in paragraph F44[(aa)] (a), (b) or (c) of that subsection, he or she shall refuse to grant the request and shall not disclose to the requester concerned whether or not the record exists.

(3) Subsection (1) does not apply to a record—

(a) if it—

(i) discloses that an investigation for the purpose of the enforcement of any law, or anything done in the course of such an investigation or for the purposes of the prevention or detection of offences or the apprehension or prosecution of offenders, is not authorised by law or contravenes any law, or

(ii) contains information concerning—

(I) the performance of the functions of a public body whose functions include functions relating to the enforcement of law or the ensuring of the safety of the public (including the effectiveness and efficiency of such performance), or

(II) the merits or otherwise or the success or otherwise of any programme, scheme or policy of a public body for preventing, detecting or investigating contraventions of the law or the effectiveness or efficiency of the implementation of any such programme, scheme or policy by a public body,

and

(b) in the opinion of the head concerned, the public interest would, on balance, be better served by granting than by refusing to grant the request concerned.

(4) In subsection (1) “penal institution” means—

(a) a place to which the Prisons Acts, 1826 to 1980, apply,

(b) a military prison or detention barrack within the meaning, in each case, of the Defence Act, 1954,

(c) Saint Patrick's Institution, or

(d) an institution established under the Children Act, 1908, in which young offenders are detained.