"In essence, he wasn't someone who went to the address with a blood lust or buck fever. He went there reluctantly."
Mr Hart said Campbell was asked to destroy the dogs and did it in a calm, almost dispassionate, manner.
"He carefully identified the target and ensuring no one was in the area."
Mr Hart asked Judge Mary Beth Sharp not to find his client guilty on the basis that the charges had not been proven.
In his opening last week, Crown prosecutor Josh Shaw said the men did not take care when they shot their neighbour's dogs.
"It was clear that they were not killed instantly. They suffered considerable stress as well as pain."
The trial continues.