Drink drivers involved in crashes are set to avoid mandatory breath testing until September 2011.
The new law which makes it obligatory for gardaí to breath test drivers at the scene of a serious or fatal accident was due to come into effect this autumn.
Attorney General Paul Gallagher believes this year's Road Traffic Act may be vulnerable to legal challenge however, and has advised postponing the new provision the new lower drink driving limit is introduced.
Transport Minister Noel Dempsey is understood to be angry at the setback as he was not informed of potential problems when the legislation was being drafted.
In the meantime, a solution may be for the gardaí to use their discretion under current law and ensure those involved in accident are breathalysed at the scene.