The EvidenzerIRL instrument has been in use as an evidential breath analyser in the application of drink driving laws in the Republic of Ireland since 2011. The result of the analysis is used as evidence in prosecutions before the Courts in per se offences of driving under the influence of alcohol as distinct from screening results at the roadside. This study aims to assist doctors, lawyers and judges in assessing drivers' failure to provide valid evidential breath specimens. Since the introduction of the EvidenzerIRL, approximately 10% of evidential breath tests annually result in failure or refusal to provide a successful breath specimen, this is an offence under Irish road traffic laws. The presence of lung disease has been given as a reason for the driver failing to provide evidential breath specimens.

The aim of this study is to assess the ability of subjects with lung disease to provide breath specimens using the EvidenzerIRL. Pulmonary function tests (PFT) were carried out on volunteers from outpatients of the pulmonary laboratory in St Vincent's University Hospital, Dublin (n = 58) and a control group with no underlying lung disease (n = 19). After the PFTs all volunteers were asked to provide breath specimens using the EvidenzerIRL. Fourteen (24%) out of 58 lung disease volunteers failed to provide a breath specimen, no one from the control group was unsuccessful. Thirteen females and one male volunteer could not successfully provide. Female volunteers were more likely to fail to provide than male volunteers. A significant difference was found between the median age of successful (62.2 years) and unsuccessful (69.2 years) lung disease volunteers. Only one PFT, percentage predicted of Forced Expiratory Volume in 1 second (FEV) had a significant difference between the mean of successful (86.6%) and unsuccessful (66.5%) lung disease volunteers. A subject with lung disease was more likely to be successful than unsuccessful. Drivers' effort and operators' guidance through the process were found to be crucial parts to a successful outcome.