Fentanyl Test Strips

As explained here,

There is a new tool to help battle the opioid epidemic that works like a pregnancy test to detect fentanyl, the potent substance behind the escalating number of deaths roiling communities around the country.

The test strip, originally designed for the medical profession to test urine, can also be used off-label by heroin and cocaine users who fear their drugs have been adulterated with the synthetic opioid fentanyl. The strips are dipped in water containing a minute amount of a drug and generally provide a result within a minute—with one line indicating positive for fentanyl, and two lines negative.

The federal government opposes distribution of these strips:
The moves have encountered opposition. Elinore McCance-Katz, head of the federal government’s Substance Abuse and Mental Health Services Administration, said the approach relied on the flawed premise that drug users would make rational choices.
 The government’s position, therefore, is that

a) we have to outlaw drugs because people are not rational enough to use them safely;

b) if prohibition makes it difficult for users to determine potency and quality, that is unfortunate;
c) but if users respond to this uncertainty by taking steps that reduce the risks, we cannot trust them to do that since they might not get it exactly right.
 And people wonder why we have an opioid epidemic.