Document, Document, Document any issues with an employee who may be exhibiting strange, erratic or suspicious behavior and;
Use the RS Checklist (provided in link)
Observations must be based on “specific, contemporaneous, articulable observations concerning he appearance, behavior, speech or body odors of the employee” as defined by the Federal Motor Carrier Safety Administration, which is a generally accepted definition.
What this means is that you should be able to specifically describe and document what you see, smell, etc.
Contemporaneous means that the behavior is happening in real time and is currently occurring. Behavior, odor, appearance indicates drug or alcohol use exists “right now” as you are a witness to it.
Articulable means that you can personally see, hear or smell it and can “articulate” your observations and express what they are.
A secondary witness should also be able to corroborate your observations and be willing to attest to your claims.