It's mandatory in Nova Scotia, the law---and a good one. "All persons hunting or attempting to hunt wildlife and any person accompanying them shall wear a cap or hat and a shirt, vest or coat of hunter orange or camouflage orange that is plainly visible from all sides. This includes all rabbit hunters. This also applies to persons snaring or trapping but does not apply to persons" (and here I paraphrase) in a tree stand or blind while bow hunting, hunting waterfowl, hunting crows on cultivated lands, hunting bear while standing or sitting near a stationary bait site, licensed fur harvesters after general open season for hunting deer, attending a dog trial or training a dog while carrying a firearm except if done on forested land during an open big or small game season etc etc.