17.—Prima facie evidence of any Order, regulation or other official instrument made or issued by the Executive Council or by any Minister who is the head of a Department of State established by this Act may be given in all Courts of Justice and in all legal proceedings in all or any of the ways hereinafter mentioned, that is to say:—

(a) by the production of a copy of the Iris Oifigiúil purporting to contain such Order, regulation or instrument; or

(b) by the production of a copy of such Order, regulation or instrument purporting to be printed under the superintendence or authority of the Stationery Office; or

(c) by the production of a copy or extract purporting to be certified to be true, in the case of an Order, regulation or instrument made or issued by the Executive Council, by a secretary or other officer authorised in that behalf by the President of the Executive Council, and in the case of an Order, regulation or instrument made or issued by a Minister, by the secretary of such Minister or of the Department of State of which he is head or some other officer authorised in that behalf by the Minister to whom such Department of State is for the time being assigned, and it shall not be necessary in either case to prove the signature of such secretary or officer or that he is in fact such secretary or officer or was in fact authorised as aforesaid.