The Fine Gael leader warned that thousands of traffic offences could be quashed if a legal loophole was not closed off by the introduction of emergency legislation.
Mr Enda Kenny said that a speeding conviction had been overturned in the District Court in Cork on the basis that the defendant was entitled to a paper print-out of the speeding offences taken by the radar gun.
"There is real evidence that up to 60,000 people convicted by this method and others will appeal their cases on the same basis. This matter should be addressed as one of urgency by the Government."
The Taoiseach, Mr Ahern, said the Department of Transport had been examining the case.
"It dismissed a speeding offence detected by a garda using a hand-held speed detection unit on the basis that no record was produced of that unit, and furnished to the accused person before the commencement of the trial for the offence."
The issue arose, he said, from the District Court's interpretation of Section 21 of the Road Traffic Act, 2003. The Department had asked the Attorney General to examine issues raised about the use of radar guns with a view to identifying whether a change to the Act was required.
"We expect to have that advice shortly. If an amendment to the Road Traffic Act is required, the Government is likely to include it in the Road Traffic Bill which deals with many related Acts and closes off loopholes on many other issues."
Mr Kenny insisted that this approach was putting the matter into limbo.
"From the driver's point of view, and the Taoiseach does not have to drive any more, the driver will ask whether he is likely to be caught if he breaks the speed limit, and, if caught, whether he is likely to be convicted.
"I have paid a fine or two in the past, having been caught by the radar gun. About 95 per cent of all penalty points relate to speeding, and in the case of the 60,000 drivers who have been caught for speeding, the majority of those offences were caught by use of the radar gun."
He said the Government should act immediately and provide certainty in legislation.
Insisting that he had no difficulty with what Mr Kenny said, the Taoiseach said there was a process involved.
"We have in preparation a very good Bill on road traffic, which not only takes account of this but several other recent judgements and will close off loopholes."
He suggested that they should wait and see the advice provided by the Attorney General.
Earlier, Mr Kenny said that so far this year 149 people had been killed on the roads compared to 133 in the same period last year. In April, 30 people were killed, representing a 30 per cent increase on the same month last year.
"All of these are tragic cases. Hundreds of people have been seriously injured. It is obvious that the positive effects of the penalty points are wearing off."
Mr Ahern said the Government would continue to provide, improve and upgrade the road structures, and enforce the legislation through Garda powers. "Obviously too many people are being killed and injured on our roads, and, therefore, we have to continue to drive that forward."
