Assembly member Mick Bates has been found guilty of attacking paramedics who came to his aid after he drunkenly fell down stairs at a Cardiff restaurant.
The 62-year-old Montgomeryshire Lib Dem AM denied three assault and public order offences on 20 January this year.
The Welsh Liberal Democrats have suspended him and begun proceedings to terminate his membership.
Bates, who has apologised, must pay fines, costs and damages of £5,490.
Cardiff Magistrates Court rejected his defence that he had a medical condition which left him unaware or responsible for his actions.
The court heard that police and paramedics were called to Charleston's Steakhouse in Caroline Street in the early hours of the morning after Bates fell down a set of stairs.
He was found slumped, smelling strongly of alcohol and with a bleeding head.
But as paramedics tried to assist Bates, he lashed out punching one in the chest and grabbing another violently by the wrist.
Soon after he was taken to the casualty unit at University of Hospital Wales, he continued to abuse and threaten medical staff.
Health care support worker Adam Warren said Mr Bates took a pair of scissors out of his uniform pocket and waved them close to his face.
Mr Warren said: "I just quickly managed to get the scissors off him. All the while I was trying to keep hold of him."
Throughout his trial at Cardiff Magistrates' Court Bates insisted he had no memory of the assaults.
Bates' defence team said he had been briefly suffering from a rare condition called automatism at the time of the incident which meant he was not aware or responsible for what he was doing.
The defence's expert witness, neurologist Dr Christopher Gardner-Thorpe, said Bates had suffered a severe head injury after falling head over heels down the stairs outside the restaurant.
But district judge Bodfan Jenkins said evidence had highlighted 68 separate instances of conscious action on the part of Bates with one alone to defeat a defence of automatism.
"I am sure he was drunk, very drunk," he said, adding that "this is a case of one over the eight".
"The defendant had one too many and it tipped him over the edge."
Outside court, Bates said: "I am very sorry. I apologise for what I did and I will continue to do my charitable works for the health service. They have saved my life many times."
During the trial, Lib Dem AM for Cardiff Central Jenny Randerson had described her fellow assembly member as a "genuine" and "disarmingly truthful gentle giant".
Bates has said he will remain an independent AM until he retires in three months.