Income, medical, rehabilitation, death, and survivor payments to workers injured on the job. State workers compensation laws, which date from early in the twentieth century, provide that employers take responsibility for on-the-job injuries. Each state defines the benefit level for employers in that state. Although these benefits were designed to be the final obligation of employers to their employees, there has been considerable erosion of this concept since the early 1970s; workers have been allowed by the courts to sue employers for various on-the-job injuries in addition to workers compensation benefits. Because workers compensation benefits are a routine and fairly predictable risk, many employers use self insurance. Some states mandate that employers buy workers compensation insurance from a state fund, but some offer a choice of a state fund, self insurance, or commercial insurance.