https://www.techdirt.com/articles/20191105/10400743328/roadside-breath-tests-are-just-as-unreliable-as-field-drug-tests.shtml

Portable alcohol testing equipment (a.k.a. breathalyzers) have been called "magic black boxes" and "extremely questionable" by judges. And yet, they're still used almost everywhere by almost every law enforcement agency. They're shiny and sleek and have knobs and buttons and digital readouts, so they're not as immediately sketchy as the $2 drug-testing labs cops use to turn donut crumbs into methamphetamines. But they're almost as unreliable as field drug tests.

Even when the equipment works right, it can still be wrong. But it so very rarely works right. Cops buy the equipment, then do almost nothing in terms of periodic testing or maintenance. A new report from the New York Times shows this equipment should probably never be trusted to deliver proof of someone's intoxication. And the failure begins with the agencies using them.