49 CFR §655.42

1. (a)The employer must conduct a pre-employment alcohol test before the first performance of safety-sensitive functions by every covered employee (whether a new employee or someone who has transferred to a position involving the performance of safety-sensitive functions).
2. (b)The employer must treat all covered employees performing safety-sensitive functions the same for the purpose of pre-employment alcohol testing (i.e., you must not test some covered employees and not others).
3. (c)The employer must conduct the pre-employment tests after making a contingent offer of employment or transfer, subject to the employee passing the pre-employment alcohol test.
4. (d)The employer must conduct all pre-employment alcohol tests using the alcohol testing procedures set forth in 49 CFR Part 40.
5. (e)The employer must not allow a covered employee to begin performing safety-sensitive functions unless the result of the employee's test indicates an alcohol concentration of less than 0.02.