Employers concerned about making costly hiring mistakes often check an applicant's references to verify employment information and to gain information about the applicant's skills, qualifications, and work habits. The results of reference checks can be invaluable to an employer as they can often unveil potential problems in an applicant. Furthermore, failure to check references can have serious legal consequences for an employer if an employee engages in violent, harmful behavior similar to that which occurred during previous employment, and which would have been revealed in a reference check. The company can be held legally responsible and fined for negligent hiring. Employers can avoid legal missteps in giving or receiving references by adopting and enforcing a reference checking policy. An appropriate policy should include informing each applicant that reference checks are made, obtaining written permission to do so, calling or writing more than one reference to compare information, and documenting all information received or given. Employers with 15 or more employees are required by federal law to keep reference check records for at least one year, including records for applicants not hired. Questions asked during a reference check should be strictly job-related and not of a personal nature. Previous employers who give positive or inaccurate information about a troubled employee during a reference check can be held liable if the employee later demonstrates similar problems in the new workplace.