Blood samples can be taken from all drivers involved in road crashes from today - including those who cannot give consent.
The measure is part of tighter road safety regulations which come into effect today ahead of Christmas. The annual Christmas road safety campaign is being lauched today.
Minister for Transport Pascal Donohoe will announce the closure of a loophole which allowed drunken drivers to avoid blood tests through being unconscious or by claiming injury.
Under the new rules, medical authorities may now take a sample from a driver who is unable to provide consent to the procedure.
A driver will be asked on regaining capacity whether they consent to the issuing of a certificate of the test results based on the sample. If the driver refuses to allow the sample to be used, the refusal will be an offence. Penalties can include disqualification from driving.
The new rules will also give the Gardaí additional powers to test drivers who they suspect are driving under the influence of drugs. Drivers can be asked to perform a range of balance and co-ordination movements under the new rules.