You may perform a drug test under your company’s policy based on reasonable suspicion of drug use. Typically, this involves five basic steps: observe, confirm, document, confront, and test. In addition, follow any state laws that apply.
Be aware that state laws vary. Before performing a non-DOT test, become familiar with any applicable state restrictions.
As this is a non-DOT test, a positive test would not have DOT consequences. However, it would have consequences under your company policy. These consequences would again depend on state law.