49 CFR §199.109

1. (a)MRO appointment. Each operator shall designate or appoint a medical review officer (MRO). If an operator does not have a qualified individual on staff to serve as MRO, the operator may contract for the provision of MRO services as part of its anti-drug program.
2. (b)MRO qualifications. Each MRO must be a licensed physician who has the qualifications required by DOT Procedures.
3. (c)MRO duties. The MRO must perform functions for the operator as required by DOT Procedures.
4. (d)MRO reports. The MRO must report all drug test results to the operator in accordance with DOT Procedures.
5. (e)Evaluation and rehabilitation may be provided by the operator, by a substance abuse professional under contract with the operator, or by a substance abuse professional not affiliated with the operator. The choice of substance abuse professional and assignment of costs shall be made in accordance with the operator/employee agreements and operator/employee policies.
6. (f)The operator shall ensure that a substance abuse professional, who determines that a covered employee requires assistance in resolving problems with drug abuse, does not refer the covered employee to the substance abuse professional's private practice or to a person or organization from which the substance abuse professional receives remuneration or in which the substance abuse professional has a financial interest. This paragraph does not prohibit a substance abuse professional from referring a covered employee for assistance provided through:
   1. (1)A public agency, such as a State, county, or municipality;
   2. (2)The operator or a person under contract to provide treatment for drug problems on behalf of the operator;
   3. (3)The sole source of therapeutically appropriate treatment under the employee's health insurance program; or
   4. (4)The sole source of therapeutically appropriate treatment reasonably accessible to the employee.