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

theregister.com

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

#191

Post by kspacewalk2 »

IG_Semmelweiss wrote: post #182
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 think we can all agree that black boxes are not desirable. But let's not jump the gun here, and assume ill-intent.... to explain something that can be attributed to negligence, or simple human error.

I agree that we shouldn't assume ill intent, but we should recognize it is a very real possibility. Ill intent comes in when you realize the simple human error. Alone, in your office, poring over code or reviewing past files. Then you weigh the impact on your career and reputation of honestly fessing up, and put it off for a while, then a while longer.

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

#192

Post by ashtonkem »

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?

Yes, yes they do. Prosecutors often campaign on being “tough on crime”, and even judges (where elected) are known to sentence more harshly during election season.

The ability for an expert witness to deliver more convictions, even if by lying, is a feature for prosecutors, not a bug.

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

#193

Post by Ma8ee »

drdrey wrote: post #160
Ma8ee wrote: post #149

Earlier quoted context omitted.

Of course prosecutors will favour expert witnesses that will help them get convictions. Why isn’t that obvious?

There are countries where the job of the prosecutor is to uncover the truth, not to convict someone at all costs: https://en.wikipedia.org/wiki/Inquisitorial_system

I know. I live in such country. But even here it is better for the prosecutor’s career with many convictions.

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

#194

Post by carlmr »

wdobbels wrote: post #141
phire wrote: post #93

> 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. First, the defence doesn't necessarily have to evaluate all 170,000 lines. They just need to find one buggy line which could potentially overturn the result.…

If their argument is that their codebase is basically unreadable, then I see why they're scared someone might find some bugs here and there.

I'd get an expert witness in there to testify basically that.

I also don't think you should code anything mission critical like this in Matlab. It's a decent language for prototyping, not for production.

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

#195

Post by kspacewalk2 »

salamanderman wrote: post #72
JoeAltmaier wrote: post #52

Earlier quoted context omitted.

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).…

Grossly oversimplifying it, but it is what my lawyer uncles say, and is consistent with what I saw as a juror on a civil trial involving many topics I'm personally an expert in, expert witnesses are paid to lie on the stand. At the very least they are paid very very well (the amount they were paid was emphasized at the trial I was at) to state only the information consistent with what the person paying them wanted to…

Of course this is the case, but rather than lying, I think it is only a consequence of selection bias. You don't see the experts rejected by the prosecution (or defence) for opinions that aren't helpful, because of course they won't be invited to testify.

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

#196

Post by akyu »

fritzo wrote: post #181

Code review is not the way to validate statistical inferences. Even during internal review of statistical inference code, committers argue correctness through a combination of readable code, readable tests, and statistical validation on a combination of synthetic and real data. While I agree the TrueAllele source should be provided, the "zero-defects" bar is neither sufficient nor necessary for correctness of the inf…

> Code review is not the way to validate statistical inferences.

But it is a way to invalidate the inference, which is what the defense is interested in.

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

#197

Post by radu_floricica »

sdflhasjd wrote: post #145
text70 wrote: post #90

Earlier quoted context omitted.

A tool designed to find people guilty is biased to find people guilty. As far as I know it is fairly easy to take a generic dna sequencer meant for healtcare diagnostics, and repurpose it for STR analysis. The only major difference between the healthcare versions and the forensic versions is the software i/o.

> A tool designed to find people guilty is biased to find people guilty. I don't see those particular issues make it biased, just inaccurate - it could go either way.

And yet somehow whenever you take a closer look at mislabeled product prices, the average is always in favor of the store. And that's far from the only industry.

Complex tools are the product of many thousands of individual decisions taken by humans, humans aware of who's the paying client.

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

#198

Post by londons_explore »

michaelt wrote: post #176
londons_explore wrote: post #56

Earlier quoted context omitted.

I would need a very very big pile of very clear cut evidence to find someone guilty of a crime where the likely outcome is a substantial prison time. It's all tradeoffs, but "his blood was found on the murder weapon" wouldn't be sufficient for me - some childhood enemy could easily have planted a bunch of forensic evidence next to a crime scene.

Unfortunately, the vast majority of crimes don't produce evidence that rises to the level you call for. After all, if my next door neighbour barged into my house and beat me up, the only evidence would be my visible injuries and my statement that it was my neighbour. I'm not sure if I'd prefer a society where he would be convicted, or where he wouldn't.

Maybe your neighbour has a nicer car than you which makes you feel insecure so you decide to beat yourself up and go to the police saying your neighbour did it.

Considering that possibility, I don't want to put your neighbour in prison.

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

#199

Post by ashtonkem »

flavius29663 wrote: post #150
abfan1127 wrote: post #120

Earlier quoted context omitted.

10 lines per hour? doesn't that seem painfully slow?

have you ever seen MATLAB code?

That’s actually a pretty good argument for banning such code from the criminal justice system. The idea that unreadable code is deciding who gets locked up is really worrying.

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

#200

Post by kspacewalk2 »

phire wrote: post #93

> 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. First, the defence doesn't necessarily have to evaluate all 170,000 lines. They just need to find one buggy line which could potentially overturn the result.…

>Second, even if it did take a full 8 years, is that a good reason to deny the defendant due process?

"It's just gonna take so long, plus the code is a bit messy. We're gonna be doing all that work just because the rest of someone's life teeters on the results of the inquiry? Maan, that's a bummer."

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