A plea for thresholds, i.e., maximal allowed levels for prohibited substances, to prevent questionable doping...

With the development of highly sensitive drug testing technologies that can detect a minute quantity of a prohibited substance in an athlete's body, accidental contamination through contact with publicly circulated materials can more readily result in a "positive" reading. To discharge the burden of a positive finding, the athlete must show the "factual circumstances" in which the prohibited substance entered his/her system. In cases of accidental contamination, the athlete generally cannot even know how it occurred, as there are many known and unknown possible sources of contamination. When an athlete does give an account, it cannot generally be proven or disproven. Outside the realm of sports anti-doping, the use of scientifically established thresholds for drug testing is standard practice. Basic logic dictates that thresholds would enable one to differentiate between relevant and irrelevant amounts in the context of a possible sports doping offence. Such a threshold should be functionally motivated, i.e., enable the differentiation between relevant and irrelevant quantities in the context of a possible doping offence, rather than based on instrument performance limits.