Except as is in this Act provided and subject to the provisions of any other law, no witness in criminal proceedings shall be compellable or permitted to give evidence as to any fact, matter or thing or as to any communication made to or by such witness, if such witness would on the thirtieth day of May, 1961, not have been compellable or permitted to give evidence with regard to such fact, matter or thing or communication by reason that it should not, on the grounds of public policy or from regard to public interest, be disclosed, and that it is privileged from disclosure: Provided that any person may in criminal proceedings adduce evidence of any communication alleging the commission of an offence, if the making of that communication prima facie constitutes an offence, and the judge or judicial officer presiding at such proceedings may determine whether the making of such communication prima facie does or does not constitute an offence, and such determination shall, for the purpose of such proceedings, be final.