Christopher Ingvaldson was the head of the social studies department at St. George's School, an exclusive private school in south Vancouver.
He was arrested and charged with possession of child pornography in June 2010 after a sting operation by Australian police.
His lawyer Ian Donaldson says even a 45-day minimum sentence is more than enough punishment.
"Minimum jail sentences don't appear to accomplish anything except to cost the public an awful lot of money, because most people within the system would say jail doesn't rehabilitate people, it doesn't make them better, it doesn't help the public," Donaldson said.
Ingvaldson was caught with about 40 images on his computer.
The Crown is looking for a six-month sentence.