Good question.
I believe in zero, and it should be zero. Unfortunately, according to the wording used in the act, the work is collectively “a significant part of the duties.” Those words must have meaning. I have to make a legislative interpretation. Unfortunately, if I set the thresholds at three hours, the court will probably say that it isn't “significant”, which means “noteworthy”.
I looked at the practices of other jurisdictions that use the same language as us. I did a quick analysis of what might be noteworthy. In my opinion, it's eight hours over a one‑month period. The equivalent of about one work day over a one‑month period is noteworthy.
It should be zero. I completely agree with you. However, this change must be made in the act. Unfortunately, I can't interpret the act to imply that the word “significant” means zero. I think that I would have a hard time winning that argument in court.
