If he’s a regulated employer, no.

A regulated employee (e.g. driver, under FMCSA) must complete the Return-to-Duty process. If he wants to return to work as a driver, he must contact a Substance Abuse Professional (SAP) and complete the Return-to-Duty process — even if he is not hired or is terminated. Your company’s drug and alcohol testing policy will determine whether s/he is terminated or offered a Last Chance Agreement.