A man threatened to put a bullet in TD Michael Healy-Rae's head in a "vicious verbal attack" as they were stopped in cars on a busy Dublin street.
Cianan Doyle (35) subjected the Kerry politician to a "tirade" of abuse as the TD was driving to the Dail in rush hour traffic.
Mr Healy-Rae told a court the "frightening" incident left him "rattled" and "afraid".
Doyle was found guilty of a breach of the peace, but Judge Michael Walsh struck the charge out, leaving him without a conviction after he made a €1,500 charity donation.
The judge said Doyle's behaviour had been "totally inappropriate and unacceptable" and it was a situation that had escalated "out of control".
Doyle admitted using bad language but denied making any threat. Mr Healy-Rae denied a defence assertion that he was driving in a bus lane at the time.
Doyle, of Beechfield Road, Perrystown, Dublin 12, pleaded not guilty to threatening, abusive and insulting behaviour.
Dublin District Court heard the accused was the front seat passenger in a car driven by his father Alan Doyle when they encountered the TD in traffic on December 4, 2018.
Mr Healy-Rae said he was travelling from Kerry to Dublin and was approaching the junction of Dolphin's Barn and South Circular Road at 8.30am.
He was in the left lane, and the lane to his right was completely free when a car pulled up alongside him, he said.
The accused was gesturing at him to roll down his own window, which he did. Both men in the car started using "very bad language" in an "awful tirade of abuse" and the accused threatened him.
"He said 'you would want a bullet put in your head' and then 'I'd do it' or 'I would do it' or something to that effect," Mr Healy-Rae told the court.
He added that he has been a politician a long time and is used to a lot of things, but what was said was "not usual banter".
He was "used to the rough and tumble of life but I'm not used to somebody telling me they would 'put a bullet in my head'".
He said he had a dictaphone and read the car's registration number into it.
"He was as angry a person as I have ever seen in my life," Mr Healy-Rae said of the accused while cross-examined by defence solicitor Michael Staines.
"He was an extremely angry and vicious person that morning, as was the driver.
"Every kind of bad word you can think of was used," he said.
Mr Staines said Mr Healy-Rae's car had his name emblazoned on it "so whether you had your cap on or not, everyone would have known it was you".
Mr Staines said the accused rolled down the window at the request of his father, who said "what would you do about the homeless" and made "politically orientated remarks like that".
Mr Healy-Rae said it was not politically orientated.
"There was one mention of the homeless, everything else was a vicious verbal attack," he said. "It was completely unwarranted." He said after they moved off, the accused had his head out the car window, still "effing and blinding and viciously agitated".
Mr Staines put it to Mr Healy-Rae he was telling half-truths and "exaggerated what happened". Mr Healy-Rae insisted he had told the truth.
Mr Staines put it to Mr Healy-Rae that he had gone into a bus lane and ended up beside the accused. Mr Healy-Rae said this was not true, and that he was stopped in a line of traffic where he was "perfectly entitled to be" when the accused's car pulled up.
"I would have gone in any lane to get away from where I was that morning," he said.
Mr Staines said it was an incident that "wouldn't have happened if you had obeyed the law and not gone into the bus lane".
Mr Healy-Rae said it was being insinuated that it was his own fault he was told he would have a bullet put in his head.
Detective Garda Sarah Keogh told Mr Staines she was unaware if Mr Healy-Rae had been in the bus lane, as it turned into a lane for traffic to go straight on 50m before the junction.
In evidence, the accused said his sister Sorcha noticed Mr Healy-Rae's car and their father asked him to roll down the window.
"My dad said, you are a greedy little man, you don't care about the people of Kerry and you don't care about the people of Ireland," the accused said.
"Mr Healy-Rae said 'do you think so?', I said 'yes, we do think so. You are a greedy effing man... you know what you are, you are a me feiner, what are you doing about the homeless situation?' And Mr Healy-Rae said 'what are you doing?'
"It was a politically orientated exchange," he said. "In hindsight, I definitely shouldn't have used bad language, but there was no threat as alleged."
He apologised for cursing. His father gave a similar account and denied using any bad language.
Judge Walsh said there was a huge conflict in the evidence but he accepted Mr Healy's account "without reservation".
"What started off as a somewhat minor engagement escalated into something far more serious than that," he said. "The accused behaved in a most rude and most offensive manner."
Det Gda Keogh said the accused had one prior conviction for assault causing harm.
Mr Staines said his client was a hardworking young man from a good family, had a degree and was doing well in his job and had a "great career in front of him". What happened was an "aberration," he said.
The judge said he was prepared to treat it as a "once off" and struck the charge out after the accused made a €1,500 donation to the PARC Road Safety Group.