Labour MP Eric Joyce has resigned as a shadow Northern Ireland minister after being banned from driving.
Mr Joyce, the MP for Falkirk, lost his licence for a year and was fined £400 after he admitted failing to provide a breath test.
He admitted the charge at Falkirk Sheriff Court, after spending the night in police cells.
Police arrested the 50-year-old MP near Grangemouth oil refinery late on Thursday night.
Kirsty Anderson, prosecuting, said guards at the Ineos petrochemical plant smelled drink on the politician's breath at about 2315 GMT.
The court also heard that the MP was "not compus mentis".
Miss Anderson said one of the guards had heard "what sounded like heavy metal rubbing very loudly".
The court heard that the MP told the guard: "I think I hit something, maybe that roundabout back there", and pointed in the direction of Grangemouth town centre.
Miss Anderson said: "The security officer was of the opinion that he was either confused, or under the influence of alcohol, and the police were contacted."
After being arrested, Mr Joyce told police he was tired, had been "up the previous night", and had just flown up from London.
Asked whether he had been drinking, he said: "I had one of those bottles of wine on the plane, but not excessive."
He refused to give a breath sample, saying he wanted to speak to a solicitor first.
Mr Joyce was charged with failing to give a sample without reasonable excuse, and held overnight before appearing in court.
At the court, his pleas of not guilty were accepted by the Crown on two further charges.
One charge was driving carelessly and at excessive speed on Bo'ness Road, Grangemouth, causing an oncoming car to swerve out of his way, and colliding with, and damaging, a roundabout road sign.
The other was failing to take a preliminary roadside breath test when required to do so by a police officer who "reasonably suspected" he had been drink-driving.
The MP was represented by duty solicitor Willie McIntyre.
Mr McIntyre said Joyce had been returning to Falkirk for a hospital appointment about a matter that was "causing him concern".
The solicitor added: "He is embarrassed. He has spent a night in the cells.
"The inevitable loss of his licence will be of great inconvenience to him, as is the publicity, and his party is not going to be at all happy about what happened.
"He apologises to all concerned."
Sheriff William Gallacher banned Joyce from driving for a year and fined him £400.
This is the second time Mr Joyce has received a driving ban.
He was banned in 2008 for six months after he was caught speeding on the M9.
Mr Joyce has been an MP since he won the Falkirk West by-election in 2000.