Fair Credit Reporting Act of 2010
The Fair Credit Reporting Act, which is a subchapter of the Consumer Credit Protection Act (15 U.S.C. § 1601 et seq.) requires employers to advise applicants if employment was denied based on a credit report.
The Consumer Credit Reporting Reform Act of 1996 imposes several obligations on employers who use credit reports when evaluating applicants or employees for employment, promotion, reassignment, or retention. Employers, before obtaining a consumer report (and this includes criminal background checks) must disclose in writing to the applicant or employee that it may obtain a consumer report for employment purposes, and secondly, secure the written consent of the applicant or employee. Note that when using a third party consumer reporting agency to request motor vehicle record checks for employment purposes, the FCRA should be followed, and notice given to the applicant or employee.
The employer must also certify to the consumer reporting agency that it will comply with the Act's disclosure requirements and that any information obtained will not be used in violation of any applicable federal or state equal employment opportunity law or regulation. A consumer report that bears on an individual's character, or mode of living and is obtained through personal interviews is known as an "investigative consumer report." The use of this type of report triggers additional disclosure requirements. Within three days of requesting such a report, the employer must mail or otherwise deliver written notice to the applicant or employee of said action. The employer must also advise the applicant or employee of his/her rights under the law, which includes disclosure by the employer of the nature and scope of the investigation. This advice must be sent no later than five days after the request was received, or the report was first requested, whichever is later. 
The Catholic University of America: Summary of the Fair Credit Reporting Act
FTC.gov: FCRA Links
Idaho Legal Aid: A Summary of Your Rights Under the Fair Credit Reporting Act
Federal Trade Commission: Fair Credit Reporting Act - Text of the Bill
JD Supra Law News: Employers Must Begin Using New Fair Credit Reporting Act Summary of Rights Form by January 1, 2013 September 20, 2012