Independent TD Clare Daly has been cleared of an offence of driving without reasonable consideration, a charge she had strenuously denied.
The case was dismissed by Judge Ann Ryan when she heard that the DPP had decided to drop the prosecution.
Ms Daly, 45, had received a summons in connection with an alleged road traffic incident at the Dublin Port Tunnel on 20 March last year.
She made her second appearance at Dublin District Court today, where the case was dismissed.
Ms Daly has described the attempt to prosecute her for a minor motoring offence as a distraction from her work highlighting malpractice and injustice.
From the outset she had intended to contest a charge for driving her car "without reasonable consideration for other persons", on a section of the southbound side of the tunnel in the Dublin 1 area.
This charge, on conviction, results in a fine only and carries no risk of a road ban or a jail term being imposed.
The incident was alleged to have occurred less than two months after the Dublin North TD was cleared of drink-driving.
She formally lodged a complaint with the Garda Síochána Ombudsman Commission about her arrest being leaked to the media.
The TD faced her first court appearance in February when her solicitor Gareth Noble said he had hoped to speak to the prosecuting garda, who is based in a city-centre station, "about this prosecution and the manner in which it was brought".
A court order was made on 12 February for the officer to provide disclosure of evidence in relation to the alleged incident.
Mr Noble had then said Ms Daly would be contesting the charge, and the case was due to go to a full hearing today.
When it was called, Mr Noble told Judge Ann Ryan that since the previous court hearing: "We received an amount of disclosure and CCTV evidence in preparation of the case."
"Last Thursday we received communication that a certain course would be taken by the DPP," he added.
A state solicitor then told the court that the DPP's direction was to withdraw the matter.
Judge Ryan agreed to a request from the defence to mark the case dismissed.
No evidence was given in relation to the alleged incident itself and the TD was not required to testify.
However after the proceedings concluded she gave a statement, in the presence her of solicitor, outside the courthouse.
Ms Daly said: "This alleged incident happened six weeks after the drink-drive arrest and subsequent exoneration and there was a lot of media attention.
"From the time it happened I was of the view that I had no case to answer and was actively seeking to defend it.
"I have been in court two days to do that. I see it as a distraction to the other important work I was going to do.
"And I will carry on taking on cases highlighting malpractice and injustice. It is unfortunate we had to come down here for two days."
Mr Noble said: "We were here ready to defend."