You have completely missed the point. Zero error is not achievable. You have to choose to accept either false positives or false negatives. In a free society, false positives are supposed to be considered the greater evil.

I have made no judgement about the relative evilness of false positives vs false negatives. I have merely stated that the dog's performance is dramatically different from that of a fair coin and that making that comparison is a misrepresentation of the facts.

It's not different in the way that matters: both produce a lot of false positives. That makes it a fair comparison despite the fact that some of the details are different.

On your quality metric, the best result would come from a two-tailed coin that indicated positive 0% of the time. But that seems to me to miss the point rather badly.

;-)

Actually, for drug offenses I'd take the two-tailed coin without hesitation. Prohibition doesn't work. Never has. Never will.

Then it sounds like your opinion on the drug war is incorrectly influencing your opinion on issues surrounding the acceptable standards for a probable cause search. While the particular example here is drugs the same questions apply on searches for guns, stolen property or any other contraband.

It's important to keep orthogonal issues separate so you don't cross contaminate and introduce unintended outcomes.

> Then it sounds like your opinion on the drug war is incorrectly influencing your opinion on issues surrounding the acceptable standards for a probable cause search

Well, you set up a straw man, so the rules of logic had already been implicitly suspended in that branch of the conversation.

> the same questions apply on searches for guns, stolen property or any other contraband

No, they don't. Dogs can't generally sniff out guns or distinguish between stolen and non-stolen property, and so dogs can't be used as a pretense in those situations. Using a dog to sniff out stolen property (unless that stolen property happens to be a salami) would make it obvious that the dog is just a pretense.

> It's important to keep orthogonal issues separate

Indeed.

So let's review: the problem is that although dogs can sniff out drugs, unless some very strict protocols are followed, they generally don't sniff out drugs and instead just tell their handler what they want to hear, i.e. that there are drugs (though, of course, the dog has no idea that this is how its actions are being interpreted. All it knows is that if it signals, it gets a pat on the head.)

As a result, dogs are not an effective crime fighting tool, but instead a de facto pretense for doing an end-run around the fourth amendment. The same effect could be produced by other means, e.g. flipping a biased coin, but that would defeat the purpose because that would make the bias obvious, which is exactly the rhetorical point that the original author wanted to make.

Do you really want to disagree with any of that?

Choosing between false positive and false negatives has a lot to do with the consequences. If you miss a drug dealer on a screening test, you missed the chance to catch the bad guy. Depending on the drug and social dynamics, this could be fairly benign (pot) or lethal (cocaine, meth, benzos, opioids). You've also communicated to the bad guy that he can get away with it. Which, given what we know of male behaviour, suggests he will push more drug more brazenly next time.

Or you could just repeal prohibition. Then drug dealers wouldn't be "bad guys" any more and you wouldn't need to catch them.

You have perhaps not autopsied many overdoses.