(b) Definitions. In addition to the terms in §§ 1500.3, 1500.5, and 1503.202 of subchapter A and § 1570.3 of subchapter D of this chapter, the following term applies to this part:

Security background check means reviewing the following for the purpose of identifying individuals who may pose a threat to transportation security, national security, or of terrorism:

1. (i) Relevant criminal history databases.
2. (ii) In the case of an alien (as defined in sec. 101 of the Immigration and Nationality Act (8 U.S.C. 1101(a)(3)), the relevant databases to determine the status of the alien under the immigration laws of the United States.
3. (iii) Other relevant information or databases, as determined by the Secretary of Homeland Security.

(c) Prohibitions.

1. (1) A public transportation agency or a contractor or subcontractor of a public transportation agency may not knowingly misrepresent to an employee or other relevant person, including an arbiter involved in a labor arbitration, the scope, application, or meaning of any rules, regulations, directives, or guidance issued by the Secretary of Homeland Security related to security background check requirements for employees when conducting a security background check.
2. (2) A railroad carrier or a contractor or subcontractor of a railroad carrier may not knowingly misrepresent to an employee or other relevant person, including an arbiter involved in a labor arbitration, the scope, application, or meaning of any rules, regulations, directives, or guidance issued by the Secretary of Homeland Security related to security background check requirements for employees when conducting a security background check.