The Director of Public Prosecutions (DPP) has lost her High Court challenge to a landmark ruling with potential implications for the prosecution of drink-driving cases.
In a recent High Court judgment, Judge Anthony Barr rejected the DPP’s judicial review challenge to the March 2025 ruling by Circuit Court Judge Catherine Staines.
Staines found defendants have a right to apply to fully inspect Evidenser breathalyser machines in Garda stations, including access to the machines’ hardware and software.
This means defendants have a stronger basis to challenge breathalyser evidence and that the accuracy and reliability of all Evidenser machines may come under increased scrutiny.
RM Block
Staines’s ruling was made on an application by barrister David Staunton for a full inspection of the machine for a man’s appeal against his July 2023 drink-driving conviction.
When arrested in May 2022, the machine recorded the man’s breath alcohol concentration at 66 micrograms per 100ml, three times the legal limit. That was after the normal 17.5 per cent reduction, allowing for variations, was applied.
Mark Jordan, a consultant forensic engineer called as an expert defence witness, told Staines a visible inspection of the Evidenser machines cannot establish their forensic integrity and a full forensic examination is necessary to verify their reliability.
As far as he was aware, no forensic integrity testing was ever carried out from when the machine was first purchased by the State in 2010, Jordan said. His view was, once the forensic integrity of the machine was established on one occasion, it should suffice as a test result for all other machines of the same make and model.
Jordan said his concerns included that software governing the Evidenser’s operation was not publicly disclosed when that was central to establishing whether the machine functioned correctly.
There are significant “real-world” examples where technology had been compromised or failed, including Boeing aircraft software issues that overrode safety features, he said.
While the Evidenser applies a 17.5 per cent reduction to a suspect’s breath test results as a safety margin, the same reduction was not applied to calibration and control tests performed on the machine, raising questions about the reliability of the results, he said.
In evidence for the DPP, Louise Lawlor, principal analyst in the Medical Bureau of Road Safety (MBRS), argued inspection would be irrelevant because the defendant’s breath was tested almost three years earlier.
Since then, she said, the Evidenser had been moved between Garda stations, used hundreds of times, and had its gas canister components replaced.
Lawlor gave evidence concerning maintenance and testing of the machine, including tests on site by the bureau every six months and monthly checks by trained Garda supervisors.
The DPP’s other concerns about a full inspection included that removing parts would compromise the machine, valued at €12,000, and that sharing the software was precluded due to commercial sensitivity.
Carrying out testing of the nature suggested on all 86 Evidenser machines could lead to an overall bill of more than €1 million, Staines was told.
The bureau was prepared to allow visual inspection of the machine, along with a simulated test involving a known quantity of alcohol being introduced into the machine to validate accuracy of the end result produced by it.
The 17.5 per cent reduction was, the court heard, based on relevant guidelines and a paper written in relation to the Evidenser and variations between 27,000 breath tests.
In his High Court decision, Barr noted the DPP had conceded it was appropriate for the defendant to inspect the Evidenser and the “real” dispute was the level of inspection.
Judicial review cannot address the merits of Staines’s decision in favour of an inspection of hardware and software and can only address whether there was an error of law involved, he said.
In finding no such error, Barr said it was open to Staines, on the evidence before her, to conclude the inspection sought by Jordan was necessary to enable him properly determine the forensic integrity of the Evidenser apparatus.
There was insufficient evidence to support the claim that full inspection was not possible under an alleged non-disclosure clause in a contract between the supplier of the Evidenser software and the MBRS, he said.
Final orders will be made in October.
