23 C.F.R. § 1.33
No official or employee of a State or any other governmental instrumentality who is authorized in his official capacity to negotiate, make, accept or approve, or to take part in negotiating, making, accepting or approving any contract or subcontract in connection with a project shall have, directly or indirectly, any financial or other personal interest in any such contract or subcontract. No engineer, attorney, appraiser, inspector or other person performing services for a State or a governmental instrumentality in connection with a project shall have, directly or indirectly, a financial or other personal interest, other than his employment or retention by a State or other governmental instrumentality, in any contract or subcontract in connection with such project. No officer or employee of such person retained by a State or other governmental instrumentality shall have, directly or indirectly, any financial or other personal interest in any real property acquired for a project unless such interest is openly disclosed upon the public records of the State highway department and of such other governmental instrumentality, and such officer, employee or person has not participated in such acquisition for and in behalf of the State. It shall be the responsibility of the State to enforce the requirements of this section.
23 C.F.R. § 1.33