28 motorists have been fined €417,500 after they failed to appear in court and ignored hundreds of warning letters about dodging M50 tolls.
The prosecutions at Dublin District Court included eight commercial vehicle owners handed fines between €19,000 and €25,000 today.
Judge Anthony Halpin described the defendants who did not come to face their cases as a "gross insult" to the court.
Transport Infrastructure Ireland (TII), the State agency dealing with road and public transport infrastructure, prosecuted them at Dublin District Court.
Most of the matters had been adjourned from last month when Judge Halpin was concerned about the number of "no-show" defendants who end up fined in their absence.
Today out of 43 cases listed, 13 were adjourned, and one was struck out.
The single defendant who came to plead guilty was described by the judge as a "rare exception" and given credit for how he met the case.
He was spared hefty fines and just ordered to pay €350 in costs after the judge noted that he had not been getting warning letters about his outstanding tolls due to marital breakdown.
The remaining 28 proceeded in the absence of the motorists who did not show up despite last month's reprieve.
Judge Halpin said he had given them an opportunity and had the cases heard earlier, fearing the usual 2pm slot had been inconvenient.
However, noting that it made no difference, he said, "It is a gross insult and disrespect to the court process".
Judge Halpin handed down fines ranging from €6,000 to €25,000 and ordered them to pay €350 in prosecution costs within six months.
He acknowledged that the court imposed heavy fines but said they focused road users' minds on paying the tolls necessary for the motorway's maintenance.
The court heard that despite getting hundreds of warning letters and being summonsed, they did not attend the hearings, which went ahead in their absence.
Van, truck and lorry owners received the most significant fines.
The private car owner with the worst record, 53 out of 520, and over a thousand warning letters, was fined €19,000.
The judge noted the types of vehicles and their records of outstanding charges. In each case, he heard the number of unpaid tolls and details of the level of engagement with the motorway operators.
The TII could demonstrate which motorists made efforts to pay for journeys, and they received less severe fines.
A truck owner, who paid for 49 out of 312 journeys, was fined €19,000, while another motorist with the same type of commercial vehicle did not pay for any of his 278 trips and was ordered to pay €25,000.
Prosecuting counsel Thomas Rice (instructed by Pierse Fitzgibbon Solicitors) said the cases could proceed against the 28 in their absence. Counsel called on a TII witness to confirm each vehicle's ownership records, the number of passages, and payment history.
The judge heard that some had recently ceased being owners of the cars subject to the prosecutions. However, the TII could establish they were the owners at the time of the unpaid tolls.
The court can impose fines of up to €5,000 per charge and a six-month sentence.
However, it remains the practice of the motorway authority to select habitual non-payers to face criminal proceedings.
The standard M50 toll for a private car, €3.20, has to be paid before 8 pm the following day, or there is a €3 penalty for missing the deadline.
Motorists get 14 days to pay for the journey and the initial penalty or face a more significant fee.
The charge ramps up after 56 days; warning letters and court proceedings follow if it remains unpaid.
Commercial and goods vehicle owners pay higher tolls. In all cases, the registered vehicle owner is liable even if they were not driving.
Reporting by Tom Tuite