Police and Criminal Evidence Act 1984

2 The first set of access conditions is fulfilled if—

(a) there are reasonable grounds for believing—

(i) that a serious arrestable offence has been committed ;

(ii) that there is material which consists of special procedure material or includes special procedure material and does not also include excluded material on premises specified in the application ;

(iii) that the material is likely to be of substantial value (whether by itself or together with other material) to the investigation in connection with which the application is made ; and

(iv) that the material is likely to be relevant evidence ;

(b) other methods of obtaining the material—

(i) have been tried without success ; or

(ii) have not been tried because it appeared that they were bound to fail; and

(c) it is in the public interest, having regard—

(i) to the benefit likely to accrue to the investigation if the material is obtained ; and

(ii) to the circumstances under which the person in possession of the material holds it,

that the material should be produced or that access to it should be given.