I can’t get a good answer for this as Google is thinking I’m talking just solely on the driver. I’m including passengers who don’t. I’ve seen PSAs that tell you the dangers you pose for others as well when you don’t wear a seatbelt. So if you don’t wear a seatbelt and that results in someone being killed could you not wearing a seatbelt mean you get a manslaughter charge?
As I understand it, getting someone killed through negligence of any kind is manslaughter.
So I’d say yes.
I don’t know if anyone’s tried to prosecute this, though. It would seem kinda mean after someone’s been in a serious accident.
Also, IANAL, but there can be factors that protect you from charges sometimes. If the driver knew you weren’t wearing a seatbelt it probably becomes their fault in my jurisdiction, and if there’s debate about who knew what that’s reasonable doubt right there.