Comment by jimrandomh | Hacker News Reader

Comment by jimrandomh | Hacker News Reader

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The actual basis of the raid was a false positive by a field test kit, which misidentified tea leaves from the target's trash as marijuana. (They claim to not need a search warrant to look at trash.)

The raid was conducted in 2012, and this article reports a test performed in 2009 which showed that the brand of test kits in question has a 70% false positive rate. It links to a video in which running the test without a sample (ie, just exposing it to air) produced a "positive" result. Notably, this was three years earlier than the raid in question, which means that they were still using the faulty test kits.

There are only two possible reasons for a police department to be using a test like that. The first is ignorance, but of a degree and nature that is quite scandalous. The second is to commit fraud upon the courts, by claiming to have evidence of drug possession where no drugs exist. In light of the FBI hair test scandal (https://www.washingtonpost.com/local/crime/fbi-overstated-fo...) I think the latter explanation is fairly likely.

> The actual basis of the raid was a false positive by a field test kit

Yes, but the reason they were being investigated at all was because a cop was recording license plate numbers at a garden supply store.

You don't even have to have something to hide to fall prey to the war on citizens. If the police need an arrest, and they're looking at you, you'll be arrested.

Exactly.

You don't know if you have something to hide.

Either because you don't know how an irrational enemy (in case govt) will interpret your actions, so you want to minimize their ability to see your actions, or you don't know what will happen in the future. Because everything is recorded these days, you don't know if in the future you might want to hide something you did today. Say, you like to drink hibiscus tea and wear blue shoes. But it turns out in the future members of some horrible terrorist group will be drinking hibiscus tea and wearing blue shoes. Then you'd be a target all of the sudden.

EDIT: This similar to how police always can search your car if they want to -- they call the K-9 unit. The handler says "find boy" or does some other trained jesture or word, dog signals, now there is a probable cause to search your vehicle. It is very hard to prove that the dog was conditioned to signal on command and hard to refute (cop's word vs yours). So that is why K-9 units are very popular with some police departments. They provide ambiguity and plausable pretext for searches.

It's really absurd that we've outsourced the Fourth Amendment to dogs.

Quoting a post I recently came across on reddit:

> The Fourth Amendment of the Constitution clearly states: "The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated unless a dog barks."

This is almost as bad as the Annie Dookhan[0] incident, in which a crime lab chemist outright falsified evidence used in almost 40,000 cases. She planted drugs in some tests, or simply faked results for tests that she never actually performed.

In at least some cases, she did this explicitly to aid the prosecution in securing convictions[1][2].

Spoiler: Dookhan got only 3-5 years worth of prison time for this.

[0] https://en.wikipedia.org/wiki/Annie_Dookhan

[1] http://www.boston.com/news/local/massachusetts/2012/12/20/in...

[2] http://www.slate.com/articles/news_and_politics/crime/2015/1...

At least she made the news. I know of an acquintance of a neighbour from many years ago, who was working as a technitian for DNA crime testing lab, which also did paternity testing, rape kits, etc. That individual was selling their services to the highest bidder. I imagine over the years, rapists, killers, deadbeat dads and all kind of horrible criminals got away while that person acquired a nice fortune. When I think of an example of a horrible example of a human being, the lowest of the low, that particular person comes to mind.

Seems like your DNA technician was only doing what most good defense attorneys do - secure an acquittal for a suspect.

And as for the argument that he was falsifying evidence to allow a guilty person to walk, I am sure that the occurrence of the opposite situation is far more prevalent - that false evidence is produced to allow an innocent person to be jailed.

We can show with a few assumptions that the police thought that the prior probability of the leaves being marijuana (before the field test) is at least 41%.

A = leaves in trash are marijuana B = field test result is positive

First use Bayes' to get P(A|B) = P(B|A)P(A) / [P(A)P(B|A)+P(-A)P(B|-A)]

Assume the false positive rate, P(B|-A) = 0.7. Assume the true positive rate, P(B|A) = 1.

The result is P(A) = 0.7P(A|B)/(1-0.3P(A|B))

Assume to get a warrant the police need P(A|B)>0.5. This puts P(A)=0.41. However, probable cause is more strict. Assume we need P(A|B)>0.90. This puts P(A)=0.86.

So if you go to a garden store and you drink tea, the police are 86% sure there are illegal substances in your home.

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