Rhetorical question? It's polygraph, drug sniffing dogs and breathalyzer. There was a court case a while back about drug sniffing dogs that presented the empirically demonstrated fact that the dogs present false positives all the time; but the judges concluded that it resulted in so many convictions that it would be a disaster to prevent their being evidence in court (analogous to witch dunkings, I suppose.) And breathalyzers are electronic devices whose source code is not auditable because the it is a "trade secret." Convicted by breathalyzer result? Can't challenge the black box's findings.