Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Accused murderer wins right to check source code of DNA testing kit

theregister.com

Post reply on HN
Print view View original

101–110 of 520 posts

Re: Accused murderer wins right to check source code of DNA testing kit

#101

Post by aaron695 »

This isn't a DNA testing kit as one would normally think -

"TrueAllele uses a hierarchical Bayesian probability model that adds genotype alleles, accounts for artifacts, and determines variance to explain STR data and derive parameter values and their uncertainty. The computer employs Markov chain Monte Carlo (MCMC) statistical sampling to solve the Bayesian equations. The resulting joint posterior probability provides marginal distributions for contributor genotypes, mixture weights, and other explanatory variables."

https://onlinelibrary.wiley.com/doi/full/10.1111/1556-4029.1...

Re: Accused murderer wins right to check source code of DNA testing kit

#102

Post by scott00 »

steerablesafe wrote: post #30

Are forensic labs often get blind tested? If there is a bias for guilty cases then it should turn out in those blind tests. Source code is a red herring here, there should be independent evaluations of forensic laboratories/methodologies/etc... regardless of software source code availability. Maybe these checks are already in place, I genuinely don't know.

I don't know the answer to your question, but blind testing is complementary to (not a substitute for) source code review.

It's very common for software to work correctly a high percentage of the time, but fail on rare input data. If, say, the software works correctly 999,999 times out of a million, you're going to be very unlikely to discover that error by throwing random samples at it, especially if you need a physical process (ie, drawing blood) in order to generate a test case.

On the other hand, once you have a known failing case (as you would if the defendant knows the result must be in error because he didn't commit the crime), it's often fairly straightforward to identify the error by reviewing the source and/or using a debugger to examine the progress of the algorithm.

Re: Accused murderer wins right to check source code of DNA testing kit

#103

Post by [deleted] »

londons_explore wrote: post #69
hirundo wrote: post #55

If an accused person has the right to see the source code that produced evidence against them, is it a violation of their rights for the source code to be obfuscated, or even just so spaghettified that not even an expert can understand it? I kinda think that should be a violation. But deciding whether a particular piece of code is so bad is so subjective that I'm not sure on how you'd make a legal standard out of it.…

You don't need a legal standard. You just need to put doubt into the minds of a jury. You can get an expert to stand up and say "I'm an expert in computers, and I couldn't understand how this DNA test works. I think it's likely there are mistakes in it that neither I nor the people that made it have discovered".

[deleted]

Re: Accused murderer wins right to check source code of DNA testing kit

#104

Post by 35fbe7d3d5b9 »

sethammons wrote: post #46
AS37 wrote: post #19

Earlier quoted context omitted.

> a forensic pathologist was giving fake prosecution evidence The doctor handled thousands of cases in his career, and a well-funded inquiry found issues with less than 1% of them. Sure we'd like that to be 0%, and society should spend time thinking of how much they rely on complicated processes of reasoning, but that's a really good accuracy.

If the error goes against innocent people, then it must be unacceptable. If the error sides with the “would-be” criminal, that is more acceptable as we, as a society, have decided that letting a few bad folks go is preferred to imprisoning innocents.

> as we, as a society, have decided that letting a few bad folks go is preferred to imprisoning innocents.

We, as a society, like to say this because it makes us feel good.

But a critical analysis of our actions reveals that we don't believe it for a second. We are happy to write overbroad laws that allow most behaviors to be criminalized, over police marginalized communities, and place those who have been convicted by this flawed system in deeply dysfunctional prisons that may well violate their human rights.

Re: Accused murderer wins right to check source code of DNA testing kit

#105

Post by yarcob »

pc86 wrote: post #31
AS37 wrote: post #19

Earlier quoted context omitted.

> a forensic pathologist was giving fake prosecution evidence The doctor handled thousands of cases in his career, and a well-funded inquiry found issues with less than 1% of them. Sure we'd like that to be 0%, and society should spend time thinking of how much they rely on complicated processes of reasoning, but that's a really good accuracy.

You say that as if these were mistakes or unfortunate culminations of circumstance. The man committed fraud and sent innocent, grieving parents to prison by proxy. I don't think it's unreasonable to expect that to be 0.00% and punish those harshly who exceed that metric.

The wikipedia page is heartbreaking. Griefing parents sent to jail, their other children taken away and placed in foster care... So many lifes made miserable by one person...

Re: Accused murderer wins right to check source code of DNA testing kit

#106

Post by buttercraft »

kortilla wrote: post #81
MaxBarraclough wrote: post #67

Earlier quoted context omitted.

The hands-off reputation-based approach isn't enough to regulate food and drugs, or aviation. I don't see why for-profit forensics companies should be trusted implicitly. Also related: we know that funding bias [0] is a real problem in science, despite that scientists' reputations should (ideally) motivate them to resist such biases. [0] https://en.wikipedia.org/wiki/Funding_bias

No, the question is what is the incentive for lying and claiming guilty? Do prosecutors choose different labs?

Paying investigators per conviction is a sure way to create incentive.

Re: Accused murderer wins right to check source code of DNA testing kit

#107

Post by jimz »

wtetzner wrote: post #37
tantalor wrote: post #29

Earlier quoted context omitted.

Why? The risk to their reputation & livelihood for a false positive should temper that.

I seems like there are no repercussions for sending an innocent person to prison. I don't know if that's true , but it definitely seems like it.

Depends on what you mean by repercussions. Since there is at least informal and sometimes fairly open scorekeeping happening at prosecutor's offices there's some hurt pride if your conviction is overturned later. Everything else either gets taken care of by the taxpayer or prosecutors' immunity for their official acts so on a personal level, no, there won't be any actual repercussions.

Re: Accused murderer wins right to check source code of DNA testing kit

#108

Post by josephorjoe »

JoeAltmaier wrote: post #52
motohagiography wrote: post #10

It's an important development. Forensic labs and companies are expert witnesses with black box processes and the incentive to protect the authority of their profession. They are as likely to lie as any other witness. Perhaps even moreso. "Those arguing on behalf of the defense cited past problems with other genetic testing software such as STRmix and FST (Forensic Statistical Tool). Defense expert witnesses Mats Heim…

I'm not so sure we should be allowing challenges to expert witness, with no evidence. That sounds like a rich source of abuse of the system, like a big company filing thousands of briefs to delay a case. It's important for experts to use validated, tested equipment. That's clear. And by the sound of it that is happening (stories of how code was tested and found wanting confirm that; stories of double-blind testing).…

defendants should always be able to challenge expert witnesses qualifications.

and how could anyone on hacker news claim there is 'no evidence' that unreviewed software may do something other than what people claim it does? especially if it 170,000 lines of matlab?

from the article:

> "Without scrutinizing its software's source code – a human-made set of instructions that may contain bugs, glitches, and defects – in the context of an adversarial system, no finding that it properly implements the underlying science could realistically be made," the ruling says.

Re: Accused murderer wins right to check source code of DNA testing kit

#109

Post by tehwebguy »

chadlavi wrote: post #89

While this may lead to more transparent technology use in the justice system, a more realistic outcome is that everyone accused of any crime where a technology was used in the process of determining guilt (which could get quite picayune; did the prosecutor's office use Excel? Is that something the defendant could demand to check the source code on?) will use this as a way to slow-roll the process indefinitely.

Well sure, if they rely entirely on Excel to generate and spit out an expert witness testimony. If that ever happens it will be extremely important to understand what’s happening under the hood in Excel.

Re: Accused murderer wins right to check source code of DNA testing kit

#110

Post by hastradamus »

The co-founder of the company, Mark Perlin, is said to have argued against source code analysis by claiming that the program, consisting of 170,000 lines of MATLAB code, is so dense it would take eight and a half years to review at a rate of ten lines an hour.

This is hilarious. As if you need to read every damn line and you can’t skip blank lines? You can skip whole files that aren’t relevant. Weak excuse

Post reply on HN