"Workers' compensation provides cash and medical benefits to workers who are injured or become ill in the course of their employment and provides benefits to the survivors of workers killed on the job. Benefits are provided without regard to fault and are the exclusive remedy for workplace injuries, illnesses, and deaths. Nearly all workers in the United States are covered by workers' compensation. With the exception of federal employees and some small groups of private-sector employees covered by federal law, workers compensation is provided by a network of state programs. In general, employers purchase insurance to provide for workers' compensation benefits. Workers' compensation has been called a grand bargain between employers and workers that developed at the beginning of the 20th century in response to dissatisfaction with the tort system as a method of compensating workers for occupational injuries, illnesses, and deaths. Under this grant bargain, workers' receive guaranteed, no-fault benefits for injuries, illnesses, and deaths, but forfeit their rights to sue their employers. Employers receive protection from lawsuits but must provide benefits regardless of fault. Recently, concerns have been raised over what some allege are cuts to state workers' compensation benefits or policy changes that make it harder for workers to receive the benefits they deserve. These cuts and policy changes may be shifting some of the costs associated with workplace injuries, illnesses, and deaths away from the employer and to the employee or social programs, such as Social Security Disability Insurance (SSDI) and Medicare."
CRS Report for Congress, R44580
Federation of American Scientists: http://www.fas.org/sgp/crs/index.html