$2 DRUG TEST
Cheap drug tests that are unreliable and prone to giving false positives are in use by police departments in the US. Some tests caution that they only give “a presumptive diagnosis". No-one would wish to be convicted on this basis: presumptive means “conjectural, speculative, tentative, suppositional, notional or hypothetical”. Nevertheless, people are arrested, convicted and fined or jailed as a result of these unreliable tests.
Image courtesy of U.S. Customs and Border Protection [public domain], via Wikimedia Commons