Some 150 speeding cases were struck out at Bray District Court today because Wicklow Council County was unable to satisfy the presiding judge that a specially-imposed speed limit had legal standing.
Motorists were charged with breaking a 60 kmh speed restriction on the N11 dual carriageway at the village of Kilmacanogue over an 18-month period.
Judge Murrough Connellan criticised the council for failing to produce documentary proof of the legality the special speed limit.
The anomaly was identified by solicitor Brian McLoughlin last February when he told the court that the speed restriction was imposed in April 2004 but the by-law giving it effect was only passed by the local council in November 2005.
Some 86 cases were thrown out at the time and as more cases appeared before the court in the following period, Judge Connellan adjourned and sought documentation about the speed limit.
Judge Connellan today said the information was of "no use" and he criticised the State for its inefficiency and the inconvenience caused to the defendants.
Today's judgment is likely to lead to the motorists who had paid a fine and received penalty applying for a refund and withdrawal of the points. Four further summonses came before the court today and were adjourned until September.
Fine Gael transport spokeswoman Olivia Mitchell said the courts could expect a "lood" of further legal challenges. "It seems that court cases involving road traffic offences are falling like ninepins," Ms Mitchell said.
She said 29 of the 34 local authorities are operating illegal speed limits and are almost certain to be challenged. The "fiasco" could have been avoided during the change-over to metric speed limits, she said.
"Every local authority should have ratified so-called special speed limits, like the one on the N11. Ludicrously, the Department of Transport had assured local authorities everywhere that there was no need to do so."
That is why Wicklow County Council waited a year and a half to ratify this 60 kph speed limit on the N11, which meant it was operating an illegal speed limit for that whole period."
Labour's Roisin Shortall said the Government and the local authorities must take responsibility for the Wicklow case and the striking out of drunk-driving prosecutions in Cork, in which eight cases have been thrown out because of the State's delay in proving the reliability of the Intoxyliser testing process.