Highly sensitive tests are great for this. They're usually cheap and quick. They have a low false positive rate so a negative result is likely to be correct.

Since they detect anything that even remotely looks like the targeted substance, they have a substantial false positive rate and a positive result must always be confirmed with specific tests. However, police forces seem to treat a positive result as sufficient cause for an arrest.

https://www.ncbi.nlm.nih.gov/m/pubmed/12423006/

Without confirmation, false positive rates varied from 2 to 4 percent.

My impression from watching too much COPS and LivePD is that police don't really see arresting people as that serious, "They'll be out in few hours". For the people they arrest most often it's probably not that big a deal either. But if it's your first ever then your lifestyle is under serious and permanent threat.

EDIT: Removed "middle class". Getting arrested is terrible no matter what your economic or class status is.

If anything, it's worse for the working class folks because they don't have a buffer, their friends and family likely don't have one either, and they are considered infinitely disposable by their employers.

Going from no criminal record to your first is a huge change of circumstance vs getting another incremental charge. I shouldn't have used the word middle class as it distracts from the core dynamic at play.

Don't use those TV shows as a reflection of reality--they're as real as any other reality TV show, which is to say it's an incredibly distorted version of reality.

It is actually stresfull to be in jail for poor people too.

It is not a game.

Bless that man!

It seemed as if he had the process down.

I made more friends in jail than I did in college. But you are right - it is no fun and it is no joke. For anyone.

Say 1 in 1000 people are actually carrying the substance you're looking for - a false positive rate of just 1% would mean that for every person you identify correctly, you'll falsely identify about 10 others.

If the dog's mentioned at all, surely normally it's background context to why the person was searched and the drug found [and if the police are lying about the finding, it's not the dog's fault!]

It feels weird that law enforcement get just avoid all of that by training dogs to alert at a handler's signal.

Any search that was enabled by a dog should be considered "fruit of the poisoned tree". Between their lack of accuracy and a dog's bias towards its handler, they should not ever serve as a basis for search or arrest.

When the justification for initial stop/search comes up in court, the dog's hit is held up as incontrovertible proof that a search was justified. Courts have upheld their use many times, all the way to SCOTUS IIRC.

This approach is far to prone to misuse by law enforcement. It's bad enough they can pull you over without cause (most states have loosely defined "irregular driving" laws), they can initiate a search of your car just as baselessly.

I think this is upside down ... the police are never going to have 'incontrovertible proof' of contraband before they do a full search by definition. If they did need such 'total evidence' to search, they wouldn't need to do the search at all ... they could just make the arrest.

And a dogs hint is not presented as evidence of a crime, merely reasonable suspicion for a search, which is what we want the tool for.

The point is to provide some degree of a reasonable basis for suspicion, after which more effort is used to determine the material outcome: either you have 1Kg of coke, or an illegal gun ... or you don't.

The entire point of the tools are to use something that demarcates reasonable suspicion; dogs, and other things, are viable tools.

If you attempt to enter a country, and you are asked where you are staying but can't provide an answer, or if you do not have a return flight - these are indications of 'reasonable suspicion' of further questioning.

SCOTUS ruling notwithstanding, I don't consider a dog a reasonable basis for suspicion. They're easily manipulated - may as well just come right out and let the police search whoever they want, because that's what dogs allow.

If dogs can indeed sniff out stuff in a manner consistently beyond random, then they are a good first pass tool.

Every tool can be misapplied or misused.

If the 'dogs' can provide a scientifically credible means for 'flagging' that's significantly above random chance, but still below the threshold 'beyond a shadow of a doubt' they can absolutely be used.

If a police officer smells the odor of marijuana in the car, or alcohol on the breath, or, for example, sees a crack pipe or 'empty beer' cans - those things are all examples of reasonable suspicion and it's the whole point.

That those powers can be abused is again a secondary issue.

Finally, is the obvious issue that there's very little harm done otherwise, the 'false flags' from either dogs or 'empty beer' cans that result in searching doesn't compromise the individuals or the community at large: a 'blow test' or a 'legal search' results in more accurate presentation of justice, not less.

That's the problem. They cannot.

" narcotics-detecting dogs and their handlers aren’t very good at discerning the presence of illegal drugs. Multiple analyses of drug-dog alerts have consistently shown alarmingly high error rates — with some close to and exceeding 50 percent. In effect, some of these K-9 units are worse than a coin flip." https://www.washingtonpost.com/opinions/2019/02/05/supreme-c...