top of page
Writer's picturePatrick Horan

How do police check blood alcohol level?

Updated: Dec 23, 2024



Gardai use several methods to measure blood alcohol concentration (BAC), depending on the circumstances:

 

1. Roadside Breath Test (Screening Test)


  • A portable breathalyser measures the presence of alcohol in your breath.

  • This test provides a quick estimate of whether alcohol is present but is not precise enough for legal proceedings.

  • It doesn’t test whether you are over the limit, just whether you have alcohol on your breath.

  • If you fail this test, you will be arrested and taken to a Garda station for further testing.

 

2. Evidential Breath Test


  • At the station, a more sophisticated evidential breathalyser is used.

  • This device provides accurate and legally admissible BAC readings by measuring the amount of alcohol in your breath.

  • The device becomes operational once the air surrounding the machine (ambient air) has been checked for the presence of alcohol.

  • If the machine detects alcohol in the air (e.g. from a previous arrested motorist) it will shut down and become inoperable.

  • Even if the machine is working the motorist may not be able to provide the required 2 breath specimens due to a medical complaint e.g. asthma.  

 

3. Blood or Urine Tests


  • If a breath test cannot be conducted (e.g., due to medical or technical reasons), Gardaí may request a blood or urine sample.

  • A qualified doctor or nurse will now be called to oversee the taking of blood or provision of urine.

  • Once the sample is taken/provided it is sent to the state laboratory (Medical Bureau of Road Safety) for analysis.

  • The results determine the exact BAC level and are legally admissible in court.


________________


Do you have a choice whether you provide a breath test or use the blood/urine route?

No. The Gardai decide.

 

 


8 views0 comments

Comments


bottom of page