The squad was called to the Karamu Rd home the man shared with his mother after she had called with concerns about her son's behaviour and mentioned there was a gun in the house.
The man came out of his house responding to the loud speaker which was used.
He was yelling aggressively and wearing boxing gloves but complied with police and was restrained and handcuffed with plastic cable ties.
The squad member had been tasked with reading the man his rights which he did while applying mild pressure to his back with his left knee to keep him there.
The constable had slung his rifle to his right side, after checking the safety catch was on to enable him to kneel.
On standing, he returned the rifle back to his front, not thinking he needed to recheck the safety catch which is what the crown based their case on.
Erin FitzHerbert and Ben Vanderkolk led the crown's case saying the constable failed to consciously ensure the rifle was safe and that he should have rechecked the safety catch ultimately preventing he unintentional discharge.
When opening their case on day one, Mrs FitzHerbert told the court this was a police shooting a member of the public, "it's controversial, it's emotional, it's even frightening".
"He did not deliberately shoot the man, but he was careless. He was unexpectedly shot while he was lying on the ground."
The constable's lawyer, Jonathan Krebs, told the court his client had not received the training he needed to adequately equip him for the front line.
"In a way he was unintentionally set up."
"The Armed Offenders Squad was short staffed, it seems corners were cut."
He said that his client was a well-respected and well-reputed officer and what he did was an accident. He said the victim should be compensated in some way by the police, but that was another matter.
Mr Krebs urged the jury to think about the context of the incident in August, 2013, as it was a key feature of circumstances that afternoon.
The crown argued the constable was well equipped for his role, the call-out was controlled and the environment was safe, "nothing was left to chance", and he had failed to maintain safety.
There was blanket suppression in place during the trial.