That’s interesting, thanks for the correction. That’s actually also concerning. Either they are are prosecuting enough people, and letting criminals go free, or the legal system is broken (or perhaps a huge cultural difference I’m missing). What is the point in hiring a defence lawyer if the chance of successful defence is so low? I can’t think of any test in my area of expertise (medicine) that has such a high success rate, meaning that false positives must be much too high for comfort.
False positives are rare in the US [0]: estimated at only 1% of incarcerations according to the Innocence Project (mentioned in HN article) and go even lower depending on who does the analysis.
Are you aware of legal systems in other countries with lower false positives?
The article said 4%, and contends that 4% is too high
and goes further to notice that convictions are mostly plea deals, and that prosecutors in many places don’t have to verify if the plea deal is based on any lab based evidence
and further finds a bunch of departments that arrest people no matter what the test result is, making your standard about “bad tests” completely moot
its a system based on total apathy and the article is saying thats the problem that should be fixed
As bad as this is, it does seem seem to be the status quo when it comes to forensic "science." I don't have any stats on hand, but it seems like more people are more worried about closing/winning cases than making sure they are not sending innocent people to jail.
99% conviction rate. Nice law but practically, if you are accused you will get convicted. I don't know why they make a mockery of their judicial system. Either a ton of bad guys don't get tried or a ton of innocent people are getting convicted.
That's an often-quoted statistic that really doesn't mean what it looks like. The main reason their conviction rate is so high is not that they have some bloodthirsty kangaroo court, but rather that charges are very likely to be dropped by the prosecution if there isn't compelling evidence certain to end in conviction, rather than the prosecution risking losing the case.
Note that the false positive rate for convictions won't necessarily match the percentage of prisoners who are innocent. The latter depends on both the rate of false conviction and the distribution of sentence lengths.
It also gives them a nice list of potential suspects that they can pin the crime on. A test which is only accurate to about 1 in 300,000 will produce a reasonably large list of people when the tested population is in the 10s of millions.
Prosecutors are going to chose the one that is most easily convicted. And that may or may not be the person who's actually guilty. It will most likely be the one who cracks the most easily under interrogation (read: trusts that the police are "helping them clear things up"). The actually guilty person would think to STFU and get a lawyer; an innocent person is going to think this "honest mistake" will get cleared up.
In general there are hoops to go through before ending in front of a court: Police must gather enough evidence against someone. This means that the police and prosecution services think the someone is likely guilty based on evidence before someone is prosecuted.
It is therefore expected that conviction rates should be relatively high whether in the UK or Japan.
However, 99% really looks like rubber stamping a decision that was already made by the police... and that's a red flag.
"In Japan, the criminal justice system has a conviction rate that exceeds 99%, including guilty plea cases. This has been attributed to low prosecutorial budgets impelling understaffed prosecutors to bring only the most obviously guilty defendants to trial."
"In Canada, the national conviction rate is about 97%. This does not include cases in which the charges are dropped, which comprise about one-third of criminal cases. Absent Quebec, the province with the lowest conviction rate, the figure is 99%."
"In China, the justice system has a Conviction rate of about 99.9%. This has been attributed to the use of torture and other coercive measures to extract confessions and pressure on courts and prosecutors."
If every time you enter the legal system and you have a 1% chance of being falsely convicted, that is a broken and dangerous system regardless of how other countries fare at that metric. Especially if you consider that certain underprivileged demographics are already at a higher risk of having more run-ins with the police regardless of their criminal state.
> But I'm not sure that's the correct metric; I think you really care about the amortized cost of a mistaken match across all N crimes. So you don't see the "paradoxical" quadratic increase.
It seems to me what we should really care about is the number of people falsely convicted, which is false-positive-rate-per-defendant * number-of-defendants. Since the size of the database (and therefore the false positive rate) is related to the number of defendants, the number of falsely convicted people increases quadratically with the number of people subjected to DNA testing.
Yes, you often see things like 99% conviction rate thrown around. 90% of cases end in plea deals anyway as most people aren't willing to use their right to trial because the time you get if you lose is often 10X what you can take on a plea deal. A vast majority of those found totally innocent through DNA evidence pled guilty to murder or rape even though they were factually innocent.
Out of those solved crimes only a percentage reaches an actual conviction for the criminal.
Well, that's literally true anywhere. Besides, a very high conviction rate indicates an unhealthy judicial system: http://www.economist.com/node/8680941
If you look at the criminal justice system as having some amount of diagnostic sensitivity at each stage in the process (having both false positives and false negatives as all systems do), then our comparatively lower conviction rate means that (assuming end-of-the-day-justice is equal), we should be even more willing to waste people's time developing cases that have no merit (because more of the diagnostic sensitivity is in the trial/conviction stage). So it's not unreasonable to assume it's easier to get a wiretap in the US than it is in Japan -- another explanation is that Japan is substantially more likely to have false negatives (as implied elsewhere -- but the false negative rate for many crimes in the US is quite high, as roughly half of all murders go unsolved). Could also be that the diagnostic sensitivity is extremely bumpy in America or Japan (read: basically one or two steps / people get an extremely high share of the criminal justice discretion).
Couple a strangely high conviction rate with a weirdly low crime rate, and you have reason to think something is off about the country's justice system.
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