A man who joined union flag protesters heading for Alliance leader David Ford's constituency office was convicted today of blocking traffic.
William Robinson denied a charge of wilful obstruction during the early days of the dispute.
But a judge at Belfast Magistrates' Court found him guilty, partially based on his own admission of having moved onto the road in Glengormley, Co Antrim.
Robinson, 27, of Derrycoole Way, Newtownabbey, was fined £150.
The court heard how up to 40 people protesting over the decision to restrict flying of the union flag at Belfast City Hall had attempted to get to Mr Ford's Carnmoney Road office on December 6 last year.
A PSNI chief inspector in charge of the public order operation said some of the crowd were masked, chanting and staging a sit-down.
He told the court protestors moved out onto the main Antrim Road where attempts were made to disperse them.
"That was met with jeering and abuse. This crowd were substantially armed with very heavy flag poles I believed could be used for weapons," he said.
The police chief accepted he did not see the defendant among those involved in the half-hour demonstration.
Robinson was instead arrested after leaving the scene by another officer who claimed she recognised him from the protest.
Giving evidence, the accused said he had been waiting for a bus home when he decided to join a crowd heading for the centre of Glengormley.
He told the court: "A woman I didn't even know put a flag around me and said 'Wrap it round you son and come for a protest'.
"I just went with the flow."
Robinson claimed he stayed on the footpath for most of the 45 minutes he was at the scene, only venturing onto the road briefly and stepping back onto the kerb when instructed by police.
"I wasn't obstructing, I wasn't in the way (of traffic) because they were able to drive past. I was near the kerb."
Twenty minutes later he was detained as he walked home, still with a flag round him because of the cold, he added.
District Judge Mervyn Bates rejected an argument that there had been no intentional offence.
"Just because you don't know the law doesn't mean you can't break it," he said.
"He was wilfully obstructing the traffic and there will be a finding of guilty."
Acknowledging Robinson's frank evidence, the judge said it was part of the reason why he had been convicted.
Imposing the £150 fine, he told the defendant: "You know you have got to avoid this kind of crowd and this kind of trouble."