I was wondering if a outside spigot is required by law to be on a house in Idaho?

I don't see any State requirement but you should check with the city or county building department, they may have a local requirement

I did not see it, but I though one was required on new construction ?

After reading 45 boring pages of Idaho code I still found nothing. However, Speedball1will love this, Idaho eliminated their code requiring dishwasher air gaps as long as the drain line is high looped. Tom are you laughing your butt off?