[EDIT: this isn't getting the (positive) karma I expected it to. Anyone has a hint?]
This article isn't nearly as convincing as the author hopes. (S)he mainly argues that drug dogs catch too many innocents to allow them to be used as "probable cause" for searches. However,
"The [extensive] review [of the Austrialian New South Wales Ombudsman] found that illegal drugs were found in only 26% of all searches that were initiated after a handler indicated that a dog alerted on the subject."
If there were a cheap-ish test that detected bombs with this accuracy, wouldn't we want to use it? Even if a few innocents would be unjustly searched?
I also agree with the author that we should look more closely at methodological issues of drug dogs; but this article is only convincing if you support the underlying premise that drugs aren't (all that) bad. (I do.)
(The article speculates that police dogs could be trained by their handlers to alert e.g. on blacks, but doesn't show that this actually happens, or that police dogs are more racist than police officers. The article also argues that dog-based evidence is not very strong, but only cites a case where it was thrown out; and "probable cause" is far weaker than "sufficient evidence to convict" anyway.)
How did we end up with bombs now? A second ago we were talking about (recreational?) drugs. Are you pulling the 'War on Terror' card here?
- '_cheapish_'
Backed up by what? What are the costs of training and keeping (feeding, medical treatment, housing) the dogs? Bringing the officers to search in the first place? What are the costs of the individuals being searched, who probably had to stop right there for quite a while and to sit back and wait.
- 'a _few_ innocents would be unjustly searched'
74 out of 100. 740 out of 1000. 7400 out of 10000. If 3/4 are 'few', where's 'half' and 'most' located on that scale?
Thanks for the explanation. Don't get me wrong, I think the War on Terror is even worse than the War on Drugs. I'll try to be clearer next time.
"Bombs" is intended to mean "something that we can all agree is really bad". I intended to say "the costs seem acceptable if they stop something really bad" (exaggerating for effect, "nobody who's not already in favour of legalisation is going to buy this argument"). Remember that many think that drugs are really bad.
(Some of the data you requested, although I don't think it helps much: http://people.howstuffworks.com/police-dog2.htm suggests that a police dog costs $8500 to acquire. Housing a dog in a shelter costs ~$3000 over the dog's lifetime, IIRC; so $15000 seems a reasonable guess at a dog's lifetime cost. I didn't find the number of active dogs or the cost of officer training, which would be required to calculate cost/successful search.
From https://en.wikipedia.org/wiki/War_on_Drugs: "In 2008, 1.5 million Americans were arrested for drug offenses. 500,000 were imprisoned." Even if we assume that this corresponds to 1.5 million successful searches after a dog alerted, you'd get 6 million searches per year, or about one search every fifty years per American. Of course, that assumes those searches will be randomly distributed; but still, if I felt that drugs were really bad and could be stopped by repression, I'd consider that a reasonable price to pay.)
> If there were a cheap-ish test that detected bombs with this accuracy, wouldn't we want to use it? Even if a few innocents would be unjustly searched?
Good point, though it's slippery slopes everywhere you look: What it if works on bombs, but only in 1% of the cases? What about 0.01%? What if we had a similar test for other, more trivial misdemeanours?
Either way, I'm sure that even fairly strict prohibitionists will agree that carrying around a bomb is a more significant threat to others, so it shouldn't be surprising that a more significant invasion of people's rights is tolerated. How much bigger the threat and how tolerable an intrusion is in each instance, that's exactly the crux of the matter. I suppose that was your point, too.
Edit: Another point: Seeing this, it's not surprising that there is such a range of opinion about it. People have very different evaluations towards the threat posed by drugs, and different people also have very different attitudes about how tolerable those kinds of intrusions are. This opens up a 2D space, where I suppose people often fall on a diagonal or end up in opposite corners.
You need a very low false positive rate for something to be useful in screening for unlikely events. We can't compute the false-positive rate here, though, because we don't know how many people the dogs "scanned"—only how many positives they gave.
Take an example: assume you have a detection technology that has a 1% false positive rate. That is, if you scan 100 people (without bombs) you get 1 positive (which is false, of course). Ignore for a moment any false negatives (people with bombs that are missed); assume the false-negative rate is 0.
Now, what is the chance of a random person you're screening having a bomb? It's very low. Consider that there are nearly a billion air passengers per year in the US, and almost no bombers. Let's say one in 200 million passengers has a bomb.
So, you screen 1 billion passengers, you get 5 true positives. You also get 1% false positives—that is, 10 million.
So, you unjustly searched (as you put it) 10 million people to catch 5 (not 5 million, just 5). And also, its not cheap anymore; you're spending a lot of time (thus money) on those 10 million useless searches.
>or that police dogs are more racist than police officers
I think the point is that police dogs are supposed to be LESS racist (and more objective) than police officers, since they can be used as probable cause for a search (unlike an officer's hunch).
Indeed. The article speculates that police dogs may pick up on their handlers' prejudices; but it does not show that. And even if dogs do pick up some prejudice, they may still be sufficiently objective to be used as probable cause.
This article isn't nearly as convincing as the author hopes. (S)he mainly argues that drug dogs catch too many innocents to allow them to be used as "probable cause" for searches. However,
"The [extensive] review [of the Austrialian New South Wales Ombudsman] found that illegal drugs were found in only 26% of all searches that were initiated after a handler indicated that a dog alerted on the subject."
If there were a cheap-ish test that detected bombs with this accuracy, wouldn't we want to use it? Even if a few innocents would be unjustly searched?
I also agree with the author that we should look more closely at methodological issues of drug dogs; but this article is only convincing if you support the underlying premise that drugs aren't (all that) bad. (I do.)
(The article speculates that police dogs could be trained by their handlers to alert e.g. on blacks, but doesn't show that this actually happens, or that police dogs are more racist than police officers. The article also argues that dog-based evidence is not very strong, but only cites a case where it was thrown out; and "probable cause" is far weaker than "sufficient evidence to convict" anyway.)