Across the United States, workers are afforded the legal right to pursue compensation if they have been injured or have become ill in the course of carrying out their prescribed job duties. Although the exact extent of the coverage afforded to workers varies according to state law, most states guarantee injured workers the right to have their medical costs fully covered by the employer as long as it has been determined that the accident, injury, or illness did in fact occur on the job and fell within the parameters defined by law. The costs of all medical treatment associated with the on-the-job illness or injury are paid directly by the company or the insurer, with no deductible or co-pay required on the part of the injured worker. Furthermore, the costs of traveling to and from medical appointments may also be covered, as are medical supplies and special therapies that are deemed to be medically necessary.