Most civil lawsuits, including personal injury and wrongful death lawsuits, are based on negligence laws, and those laws are left up to states to decide. In general, to hold a person responsible for negligence that caused injury or death, a number of things have to be proven.
First, you have to prove that the person whose negligence injured you owed you a duty of care. For example, a driver has a duty not to drive recklessly and thereby put your safety at risk. If you are injured by a reckless driver, then that driver breached his or her duty of care.