I stand corrected. However, if there is an allowable level of a substance, then the test must be able to determine that level to be a useful test and pilots must be given guidance as to what will lead to exceeding that level. Blood alcohol tests give a reading that can be translated into a reasonable assumption of impairment. We all know roughly how many drinks will put us at what level and how many hours are required for the alcohol to leave the system. If you tie one on, eight hours won't cover it so we don't get smashed the night before a flight. The screening allows for a BAC of 0.02. How many Panadene Forte can you take in a given time? If the answer can't be given then the answer is none and any over the counter medication becomes unusable because it might contain codeine, pseudo ephedrine or some other formally legal substance. We pilots obviously need unlimited sick leave as enjoyed by ATC. As a sample returning a positive is retested with more sophisticated equipment, the test should be made with the appropriate equipment in the first instance. Once you have tested positive, regardless of the fact that it was a false positive, you have a stigma that will follow you for the rest or your career. The appropriate equipment is available but not the money to use it so we are subject to second rate testing.