He previously pleaded not guilty to the charge which stated: “Without lawful excuse and without claim of right, knowing a letter to contain a threat to damage property, namely a building, office and house, secured the said letter to 318 Moray Pl and caused the said letter to be received by members of the public”.
Judge John Macdonald remarked it was an “unusual” charge.
Defence counsel Anne Stevens said the allegedly illegal item was not a “letter” but a poem.
The judge was given a copy of the note attached to the building and expressed some scepticism.
“That's a poem, is it?” he said. “Looks like a threat.”
“There will be quite extensive legal argument about artistic expression and poetry,” Mrs Stevens said.
She said there had been similar cultural statements through the ages, referencing the music of The Beatles and Jefferson Airplane, “even going back to Ovid”.
“I confidently say it can be established this was artistic expression and it was legitimate,” Mrs Stevens told the court.
Much of the central city had been evacuated and cordoned off for hours as police assessed the threat on June 16, with numerous businesses affected.
The New Zealand Defence Force’s explosive ordnance disposal squad was flown by helicopter to the city and destroyed the package in a controlled explosion carried out by a remote-controlled robot shortly after 5pm.
Barnes was remanded on bail and will next appear in court in October for a two-hour hearing.
He refused to comment on the allegations outside court.