What happens to my case if I wasn’t wearing a seat belt in the car accident?

It is possible that in your law suit against the negligent driver there will be a finding of contributory negligence against you and your damages will be reduced.

Contributory negligence applies to cases where, through their own negligence, plaintiffs have contributed to the damages they incurred.

So for example:
If you weren’t wearing your seat belt you may be found 25% contributory negligent. Your damages award would then be reduced by 25%.