Protesters have gathered outside the Wellington District Court where 15 peace protesters are on trial.
A 16th peace protester has been made eligible for diversion.
The judge-alone trial has begun before Judge Mill.
Prosecutor Catherine Gisler said there were nine charges of trespass, five of obstruction, and one disorderly behaviour.
Those on trial today have pleaded not guilty to charges of obstruction and trespass.
Lawyers Michael Bott, Chris Tennet and Daniel Vincent are representing some of the group in court, while others have chosen to represent themselves.
Gisler said the issues with trespass were "varied".
There were issues over the interpretation of who the "occupier" was in the trespass charge, whether police had the requisite authority to trespass the protesters, and whether the warnings for trespass were reasonable and consistent with the Bill of Rights Act.
There was also a dispute over whether there was any actual obstruction, whether the police officers involved were acting in execution of their duty, and whether the officers' actions were lawful, Gisler said.
Outside about 11 protesters are gathered in the blustery weather, holding signs that say "Refugees welcome, arms dealers not".
Other signs say "arms trade death trade" and "war starts here, let's stop it here, no weapons expo".
The 16 were among 27 people arrested in 2015 after blockading the New Zealand Defence Industry Association's Weapons Conference, an event principally sponsored by American arms manufacturer Lockheed Martin.
An anti-arms trade demonstration will take place outside court and a petition opposing the continued existence of the conference will be presented to Parliament tomorrow.