The problem is that low-quality evidence causes both type 1 and type 2 errors.

Not only does it cause significant problems for people who are unjustly jailed and charged for crimes they didn't commit -- but it also lets drunk drivers off the hook when the flimsy evidence fails to convict. These aren't hypotheticals, both are very common.

Police in the US simply need to be equipped with roadside chemical tests for substances. They exist, they just simply don't use them.

Here's is an example of what other countries do:

https://adf.org.au/insights/roadside-drug-testing/

> The officer takes a sample of your saliva by placing an absorbent collector in the mouth or on the tongue. The sample is then analysed at the roadside. If the test is positive, it must be confirmed by laboratory testing before charges can be laid.

Doesn't that sound like a better solution than: "The officer makes you stand on one leg and say the alphabet backwards, if they don't like they way you did it, you are charged with DUI"?

> I'm sure you can construct a hypothetical case where a person with a speech impairment, an inner ear deformaty and who's eyes shake when moving left and right gets arrested for DUI because they appear impaired but they weren't pulled over for those reasons.

The more common, and even more scary issue, is that sometimes people undergoing medical emergencies are arrested for DUI and sent to jail instead of a hospital. Which is again another situation that would be avoided entirely by roadside testing. This is such a common issue for diabetics that police normally do train to recognize the difference, but since they are not medical professionals and don't have adequate equipment, they still often confuse the two.

Watch this dashcam video: https://www.wsmv.com/2025/10/02/retired-deputy-arrested-dui-...