If the DOT test is a followup/return to duty test due to a previous DOT test being positive for a drug, you will be observed for the followup test (see § 40.67 of the DOT regulations).

And keep in mind that for the observed test, they will check for artificial prosthetic delivery systems and synthetic urine/substitution containers. Under § 40.67, the donor must lower trousers, undergarments, roll the shirt up, and showing the observer by turning around 360 dg, that he/she is not carrying such devices. If no devices are found, then the observer and donor proceeds to enter the bathroom stall. The observer is to directly watch the flow of urine exit the body and into the sample cup.

Before the followup/return to duty test, the donor must complete the SAP process as outlined under Subpart O of 49CFR Part 40 of the regulations.