Newly released figures show that just four in ten drink driving cases listed before the District Courts since January 2013 resulted in convictions.
The Irish Times reports the figures from the Department of Justice also show that for the first five months of this year the rate of conviction was just under three in ten, or 28%.
It is in stark contrast to England and Wales, where 97% of all drink driving cases result in conviction.
Of those convicted, just two in ten had their licence numbers recorded in court for endorsement.
A road safety expert says lawyers are looking to take advantage of 'loopholes' in the Road Traffic Act to help their clients escape drink driving convictions.
Noel Gibbons, Mayo County Council's Road Safety Officer, says many lawyers are actively challenging road traffic legislation.
He said: "I suppose it is the most fought piece of legislation in the country and and I suppose the legal eagles in the country are looking for loopholes.
"But we need to highlight the consequences of drink-driving, it has taken life, in the cases of one in four people killed on the roads there is alcohol involved, so we need to make people aware."
Evan O’Dwyer of O’Dwyer Solicitors in Co Mayo says gardaí have a process of 50 or 60 hurdles to get through before a conviction can be successful.
He says that makes it simple for experienced defence solicitors to challenge cases.
"It's like the Grand National - they have to clear every single hurdle in order, and if the gardaí fail to clear one of the hurdles the prosecution will fall, the accused will get the benefit of the doubt and the case will be struck out," he said.
"It's a very technical type of offence so if people know what they're about and if the gardaí make a mess of something, which otherwise would be seen as insignificant, then it can come back and they get the benefit of it."