the influence or reasonably if it had been ingested or smoked within a time period relevant to an accident. A positive for marijuana can be detected for many months after use with a hair test even though no THC will show up in a blood test. Unless someone shaves all body parts and removes their fingernails and toenails. Marijuana shows up in fingernail clippings also long after somebody said, "ere".
The problem is in an accident situation can the person prove that they were not effected by it if the blood test shows THC in the blood stream. Then you get into medical expert testimony based on the amount of THC, the individual make up of the person and on and on.
But as you indicate, if the company has a 0 tolerance. The employee passed a drug test for purposes of employment then his baseline of negative is when he went to work so any trace of an illegal drug in his system after start date is grounds for immediate dismisal accident or not. Many a soul has packed their box and departed after a random drug test.
Keyword where marijuana is concerned. The last time i looked it was still considered an illegal drug in the U. S. so if it's there in any trace in a workplace accident the recreational toker is toast both as to the accident and Workers Comp and also out of a job in most cases. The argument for or against the level of effect is moot if the THC level is there in the blood test. Most testing after an accident is much more through than just a simple urine sample both on the part of the company risk management group and workers comp from what i have heard from the lawyers and the lab folks.…