21. â(1) A duly completed statement purporting to have been supplied under section 17 shall, until the contrary is shown, be sufficient evidence in any proceedings under the Road Traffic Acts, 1961 to 1994, of the facts stated therein, without proof of any signature on it or that the signatory was the proper person to sign it, and shall, until the contrary is shown, be sufficient evidence of compliance by the member of the Garda SÃochÃ¡na concerned with the requirements imposed on him by or under this Part prior to and in connection with the supply by him pursuant to section 17 (2) of such statement.”
This section is, of course, of immense benefit to a prosecutor. It permits the proof of two matters in one fell swoop, each of which, if required to be proved in some other fashion would generate multiple occasions or opportunities for the prosecutor to slip on the proverbial banana skin.
In Fitzpatrick, the prosecution, for undisclosed reason, did not produce the Lion Intoxyliser machine certificate. (the Section 17 certificate). Instead, the prosecutor gave evidence of the readings obtained from the machine.
The High Court was asked to rule on the proposition that the readings could only be proved by the production of the machine readout.
The court said no. Secondary evidence could be given of the reading.
However, referring to Primor plc v Stokes  2 I.R. 459 the judge pointed out that the prosecutor, in meeting the burden of proof with secondary evidence was obliged to first establish the circumstances in which such proof could be availed of. Those circumstances are set out in Primor as follows:
The contents of a document may be proved by secondary evidence if the original has been destroyed or cannot be found after due search. Similarly, such contents may be proved by secondary [evidence] if production of the original is physically or legally impossibleâ¦â?
The prosecution, in failing to prove the circumstances in which the certificate was not produced was not to be permitted to give secondary evidence of the reading.
The judge also referred to Section 30 of the Criminal Evidence Act 1992, which reads:
where information contained in a document is admissible in evidence in criminal proceedings, the information will be given in evidence, whether or not the document is still in existence, by producing a copy of the document or of the material part of it, authenticated in such a manner as the court may approveâ¦.â?
Thus, if the prosecution had lost the original readout but had a copy, the copy (duly authenticated) would have been admissible under Section 30.