HUNDREDS of motorists convicted or accused of drink driving and other offences may have their cases overturned or thrown out of court as a result of a new legal challenge.
It follows a case in Co Donegal in which the judge is being asked to rule on whether a checkpoint set up by gardai in which an alleged drink-driver was arrested was legal.
The solicitor behind the legal challenge has already had one case struck out, the Irish Independent has learnt.
The latest challenge, due on January 20, could spark a raft of appeals from motorists convicted as a result of being stopped at checkpoints since 2004.
Others who have been charged but have yet to appear in court could also have their cases struck out.
Judge Paul Kelly sat late to hear the case at Letterkenny District Court last week.
Before the court was Sean McKeown, from Abbey Park, Manorcunningham. Garda Tara Clinton Quinn gave evidence that she arrested 40-year-old Mr McKeown at 11.30am on November 13, 2011 in the townland of Raymoghey, Manorcunningham.
She said that she had asked the defendant if he had been drinking, and he had admitted having nine pints the night before and had stopped drinking at 1.40am.
Mr McKeown had failed the breath test, was arrested and taken to Letterkenny Garda Station. His solicitor Ciaran MacLochlainn, however, argued for the case to be struck out, claiming the garda checkpoint was illegal.
He said the Mandatory Alcohol Testing (MAT) checkpoint was unlawful because the document authorising it -- signed by a superintendent -- had listed three different townlands in Co Donegal.
The Buncrana-based solicitor, quoting the legislation, said: "An authorisation shall be in writing and shall specify the date on which and the public place in which the checkpoint is to be established."
He told Judge Kelly: "It is clear that once an officer above the rank of inspector has signed authorisation for a MAT checkpoint that it must only specify one public place and one only.
"The law does not allow for multiple choices for gardai below that rank and in this case that is precisely what the authorisation allowed for.
Mr MacLochlainn also told the judge that he had challenged the law in a similar case in Buncrana. In that case, he said, the authorisation named the townland of Ardraven, which covers most of the town of Buncrana.
"It should have stated an exact location, a street name, but it didn't. I appealed the case to the Circuit Court but before the case went ahead I received a call from the State Solicitor to say the case was being dropped," said Mr MacLochlainn.
It is understood senior gardai no longer give officers mult-iple choice authorisation forms for MAT checkpoints and now specify the exact location.
At the court hearing, Garda Inspector Michael Harrison -- who is also the head of Co Donegal's traffic division -- argued the checkpoint was legal.
However, he asked for the case to be adjourned until January 20 so he could seek further legal advice.