Mont. Code Ann. § 39-2-209

The employer shall provide an employee who has been tested under any qualified testing program described in 39-2-208 with a copy of the test report. The employer is also required to obtain, at the employee's request, an additional test of the split sample by an independent laboratory selected by the person tested. The employer shall pay for the additional tests if the additional test results are negative, and the employee shall pay for the additional tests if the additional test results are positive. The employee must be provided the opportunity to rebut or explain the results of any test.