Chain of Custody Requirements in Irish Drink Driving Cases
Published by Michael Daly BL – www.michaeldaly.ie
Published: 12 September 2025
This commentary draws on material from Michael Daly BL’s book Drink and Drug Driving in Ireland (Lonsdale, 2023), which was cited with approval in Ratinskis v DPP [2025] IEHC 428.
Michael Daly BL is a practising barrister specialising in road traffic law with particular emphasis on drink driving, drug driving and drunk driving.
This commentary reflects the law as of 12 September 2025.
The Ratinskis Decision
The recent High Court judgment in Andrejs Ratinskis v DPP [2025] IEHC 428 (citing Daly, Drink and Drug Driving in Ireland, at para. 39) has clarified key evidential requirements in drink driving prosecutions, particularly regarding the chain of custody for blood and urine samples.
The applicant was stopped at a Mandatory Intoxicant Checkpoint (MIT) in Newbridge by Gardaí in 2022. He was arrested pursuant to s.10(7) of the Road Traffic Act 2010. He was brought to Newbridge Garda Station where, following a demand by a Garda, he provided a blood specimen to a designated doctor.
Kits (brown cardboard boxes), containing the equipment required by the doctor to take the sample of blood or urine, are supplied to Gardaí by the Medical Bureau of Road Safety (MBRS). They contain, among other things, a syringe, two glass bottles, seals and a form (colloquially referred to as a s.15 certificate) for completion, in duplicate, by the doctor. This procedure is provided for in section 15 of the Road Traffic Act 2010 and is headed “Procedure regarding taking of specimens of blood and provision of specimens of urine.”
The designated doctor halved the specimens into two glass bottles, sealed them and handed the two containers to Garda Houlihan. In line with the statutory procedure he (the Garda) gave the applicant the option of choosing one sealed container (which he did) and placed the remaining one and the completed form in the marked cardboard box and sealed it. This was posted to the Medical Bureau of Road Safety who analysed it and returned to the Garda station a certificate (“s.17 certificate”) certifying a concentration of 126 milligrams of alcohol per 100 millilitres of blood. This is in excess of the permitted concentration of 50 milligrams of alcohol per 100 millilitres of blood as provided for in section 4(2)(a) of the Road Traffic Act 2010.
As a result he was prosecuted for an offence of having excess alcohol in his blood.
In his direct evidence, the Garda did not account for the custody or whereabouts of the specimen from the time it was taken until the time it was posted. (Normally in these situations, the specimen is sent by registered post or in some instances hand delivered by the Gardaí directly to the Medical Bureau of Road Safety). Neither was he cross-examined in relation to this matter.
At the end of the prosecution case, the applicant’s solicitor sought a direction from the District Court Judge submitting that the chain of custody of the specimen was not complete as no evidence had been provided as to where it had been stored and evidence was not adduced by the prosecution. This was refused by the District Court Judge.
Following an ex parte leave hearing, leave was granted by the High Court permitting the applicant to apply for relief by way of judicial review, being inter alia an order of certiorari quashing the order of the District Court.
Section 15(4) and 17(4) of the Road Traffic Act 2010 contain a presumption that in the prosecution of intoxicant offences, the preceding subsections have been complied with “until the contrary is shown.” Normally these are admitted by way of certificate evidence. The practical application of this is that the authors of the forms are not required to attend court and give evidence. It relieves the State Authorities (Gardaí and DPP) of having to call witnesses to give oral evidence.
Statutory Presumptions Explained
The Road Traffic Act 2010 creates presumptions that certain certificates are admissible as evidence without further proof:
- Section 15(4) provides that in a prosecution for an offence under this Chapter or section 4 or 5 it shall be presumed until the contrary is shown that subsections (1) to (3) have been complied with.
- Section 17(4) provides that in a prosecution for an offence under this Chapter or under section 4 or 5 it shall be presumed until the contrary is shown that subsections (1) to (3) have been complied with.
- Section 20(2) provides that a duly completed certificate under section 15 shall, until the contrary is shown, be sufficient evidence in any proceedings under the Road Traffic Acts 1961 to 2010 of the facts stated in it, 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 designated doctor or designated nurse concerned with the requirements imposed on him or her by or under Chapter 4.
Decision
Judge Sara Phelan held that the statutory presumptions as provided for in s.15(4), s.17(4) and s.20(2) of the Road Traffic Act 2010 cannot assist the prosecution where chain of custody evidence was not led in the District Court. Certificate evidence cannot “plug the gap” and an order for judicial review was appropriate in the circumstance. The applicant was entitled to an order of certiorari quashing the order of the District Court.
She went on to hold that where the court has identified an inconsistency between the extent of the presumption and its application in the present case, it is a matter for the State or for the Oireachtas, as the sole and exclusive law maker in the State, as to the manner in which the inconsistency is addressed given that her judgment is likely to be of wider application than simply the present case.
Broader Legal Implications
The Ratinskis decision reinforces the importance of clear evidential procedures in criminal prosecutions. Each case must be assessed on its own facts and evidential foundation.
Impact of Decision
This decision may be appealed to a higher court. The practical effect is that cases (not all) are being adjourned in District Courts throughout the country pending the result of any appeal that may be taken.
Chain of custody evidence in drink driving prosecutions is likely to be probed by defending barristers and solicitors.
Disclaimer: This article is provided for general information and commentary on legal developments. It does not constitute legal advice. Professional advice should be sought in relation to specific circumstances.