A man made "vile" threats to kill a garda, then headbutted him on the nose after officers arrived at his home with an arrest warrant.
Francis Grogan (26) swung his fists while standing behind his mother before assaulting the garda.
Judge John Cheatle found him guilty and adjourned the case for a probation report.
Grogan, of Ball's Lane, Halston Street, had admitted obstruction but denied assaulting Gda Paul Madden in an incident at his home last March 3.
Dublin District Court heard Gda Madden went to the accused's home with a warrant and showed it to Grogan who had opened the kitchen window.
Grogan said he was "too busy" and would go to the garda station the next day. He then locked the porch door and shouted "Ha ha".
The door was answered by Grogan's mother and the accused reappeared and said he was going to kill Gda Madden.
Officers heard him rummaging around inside and the sound of cutlery or knives.
He stood behind his mother, "swinging his fist directly under Gda Madden's jaw".
He had to be restrained, and while this was happening he headbutted the officer.
Gda Madden said he did not need medical treatment after the assault but he took the threat seriously.
Grogan admitted he was "aggravated", but claimed the gardai grabbed him on the stairs and pinned him down.
He denied swinging his fists at Gda Madden, headbutting him or threatening him. He said the first he had heard of the threat allegation was in court.
Judge Cheatle found Grogan guilty and said he had made "vile and abusive threats."
Grogan had previous convictions and had never worked.