A grandfather caught with a "significant knife" tied around his neck on a shoelace insisted it was a tool he used in his work as a skip diver.
Anthony Doyle (52) denied that the knife found hidden on him when he was stopped by gardai was a weapon.
Judge Michael Walsh found him guilty and gave him a three-month suspended sentence.
Doyle, with an address at Mercer House, Mercer Street, pleaded not guilty to unlawful possession of a knife.
Dublin District Court heard gardai stopped and searched the accused at the North Circular Road on September 10, 2019, then brought him to a Garda station.
On arrival in a patrol car, a knife with a sharply pointed blade was found hanging around his neck on a shoelace, inside his shirt.
His defence barrister said a bag the accused was carrying at the time had tools in it. The accused worked "diving in skips" picking up bits of metal to be sold on, he said.
He had the knife for that purpose - to cut things out of skips, he said. He had told gardai he had the knife for work.
The garda said here was no sign of a van when Doyle was stopped. The knife was hidden and he did not accept that it was a work tool.
Judge Walsh asked how a knife around the neck could be hidden and said people might have lanyards or other work items around their necks.
The garda said the accused's pockets were searched but the neck was an area of the body that would not usually be searched.
Doyle said in evidence the knife was a work tool and he would use it to cut scrap wire, ropes and plastic. Having it on him saved him running up and down to the van, he said.
He had just jumped out of a van at a set of traffic lights and was going to meet a woman when gardai stopped him. He had not had a chance to take the knife off and put it in his bag, he said.
Judge Walsh said it was "quite a significant article" that was unusually attached to a shoelace and was not the kind of knife that would be used for domestic purposes.