In car accident claims in Nova Scotia, even if the defendant is completely at fault, Nova Scotia courts will likely deduct a percentage from any damage award if you fail to wear a seatbelt. Usually the deduction is between 5-25% of the damage award.
In 2003, the government of Nova Scotia codified the following in the Automobile Insurance Contract Mandatory Conditions Regulations, NS Reg 181/2003:
10 (1) Limitation where seat belt not worn – Unless exempt by law from the requirement in the Motor Vehicle Act to wear a seat belt, where an injured person was not wearing a seat belt at the time of an incident, there shall be a reduction of at least twenty-five per cent in damages for bodily injury or death arising directly or indirectly from the use or operation of an automobile in respect of the incident
(2) In this condition, “seat belt” has the same meaning as defined in the Motor Vehicle Act.
In the case of Hawes v. Yorston,  N.S.J. No. 29, the plaintiff was injured in a motor vehicle accident and failed to wear his seat belt. The court found that the plaintiff likely would have avoided the injuries to his shoulders had he been wearing his seat belt, and reduced his damage award by 20%. The court did not comment on section 10 of the Automobile Insurance Contract Mandatory Conditions Regulation.