Workers' Compensation as a legal issue emerged in the United States in the early 1900s. Prior to the establishment of codified workers' compensation laws, the only compensation or remedy for an injured employee was to bring a negligence suit against his or her employer. The major drawback to this type of remedy was that the employee had to prove negligence on the part of the employer, which was sometimes difficult to do. In addition, the employer used several legal defenses, which included: assumption of risk, contributory negligence, and fellow-servant rule. The very first workmen's compensation law passed in the United States was the Federal Employer's Liability Act. Workers' compensation insurance premiums represent a significant line item on any business' profit and loss statement. Insurance companies who provide workers' compensation coverage now use an additional multiplier known as the Experience Modification Rate (EMR) or Experience Modification Factor (EMF) to assist in the determination of the cost of workers' compensation costs.