Mandatory drug testing entered American life through two separate historical routes. The first was through the common law system, employing precedents philosophically derived from the idiosyncratic rules governing the “king’s forest” and the “king’s highway”. From these arcane precepts are derived the laws which allow legal authorities to detain and test persons under suspicion of driving under the influence of a psychoactive drug.
Post-incident drug testing is not a very commonly administered test compared to the other two, but the financial ramifications of not testing employees after an accident (or other incident) on the job makes this test worthwhile for most businesses.
Random drug testing is the most effective format. In the USA, random drug testing is used by a growing number of