To our resident legal beagles, lets say it is mandated, and in gravest extreme, the smart gun fails to fire. And its not some user responsibility issues (battery life, etc). Lets say there is no detectable fault in the mechanism, but it didn't work.
WHO is at fault, the maker? or the law requiring you to use a defective product? Is your estate going to go to court for damages because you had dirty hands? (gun didn't read your fingerprints?) Or because the magic watch was an inch too far from the gun when you needed it most?
Create your own sceneario. Base question is, if required by law, and it fails (not your fault) can the law be responsible in some degree?
(in that type of situation, I would want to be able to sue the individual people who passed and enforced the law, but I know that isn't remotely realistic)
Or would it be treated like car seatbelts? Law says you have to have them, law says you have to wear them, but if they don't save your life, its just your tough luck?