The troubling flaws in forensic science

by Linda Geddes in BBC Future

“It has long been an axiom of mine that the little things are infinitely the most important.” So said the fictional detective, Sherlock Holmes. Armed with his finely honed skills of backwards reasoning, his trademark ability to solve unsolvable crimes often hinged on his revealing evidence too small to be noticed.

Holmes was an inspiration for the very founders of modern day forensic science. As the decades passed and the tools in their armoury grew, so too did the sheen of invincibility that surrounded their discipline. But there was a crucial chink in their methods that had been overlooked: subjectivity.

While the likes of Holmes’s successors in detective fiction may lead us to believe that forensic evidence is based on precise deduction, all too often it relies on a scientist’s personal opinion, rather than hard fact.

Science on trial

Consider the following case. In December 2009, Donald Gates walked out of his Arizona prison with $75 and a bus ticket to Ohio. After serving 28 years for a rape and murder he didn’t commit, he was a free man. Now the spotlight began to shift to the forensic technique that put him there: microscopic hair analysis.

Human hair is one of the most common types of evidence found at crime scenes. During the 80s and 90s, forensic analysts in the US and elsewhere often looked to the physical differences between hairs to determine whether those found at a crime scene matched hairs from a suspect – like Donald Gates.

When he stood trial in 1982, an FBI analyst called Michael Malone testified that hairs found on the body of the murder victim – a Georgetown University student called Catherine Schilling – were consistent with Donald Gates’ hairs. He added that the probability they came from anyone else was one in 10,000.

“That’s very compelling evidence, particularly when it comes from a witness wearing a white laboratory coat,” says Peter Neufeld, co-founder of the Innocence Project, a New York-based non-profit organisation that uses DNA evidence to overturn wrongful convictions.

The FBI is now reviewing several thousand cases as DNA testing sheds new light on the truth (Credit: Getty Images)

However, hair analysis is not purely objective; I might think two hairs look identical, but you might disagree. Even if we agree that two hairs match, no-one has ever figured out how many other hairs might be similarly indistinguishable from one another. “When a person says that the probability is one-in-10,000, that’s simply a made-up number,” says Neufeld. “There’s no data to support it.”

Donald Gates was finally exonerated when DNA testing revealed that the hairs didn’t belong to him after all. Two similar exonerations followed soon afterwards. As a result of these cases, the FBI is now reviewing several thousand cases in which its scientists may have offered similarly misleading testimony. Last month, it announced that of the 268 cases it has reviewed so far that went to trial, 96% them involved scientifically invalid testimony or other errors by FBI agents. Among those convicted, 33 received death sentences, and nine have already been executed.

The FBI’s review won’t necessarily overturn the convictions, but it does mean that they need to be reconsidered carefully. Lawyers scrutinising these cases must work out what other evidence was presented in court; if they hinged on flawed hair testimony, retrials and exonerations may follow. In cases where the original physical evidence still exists, that DNA testing may shed new light on the truth.

Damning report

Even trusted lines of evidence, such as fingerprint analysis, are not water-tight. Research has shown that the same fingerprint expert can reach a different conclusion about the same fingerprints depending on the context they’re given about a case.

Based in part on these findings, in 2009 the National Academy of Sciences in the US published a report on the state of forensic science. Commissioned in response to a string of laboratory scandals and miscarriages of justice, its conclusions were damning. “Testimony based on faulty forensic science analyses may have contributed to the wrongful conviction of innocent people,” it said. “In a number of disciplines, forensic science professionals have yet to establish either the validity of their approach or the accuracy of their conclusions.”

The report was a wake-up call, not just for forensic scientists in the US, but around the world. “What it exposed were significant scientific deficiencies across many of the different methods that we use, both to examine and interpret different types of evidence,” says Nic Daeid, a professor of forensic science at the University of Dundee in Scotland. 

Of all lines of forensic evidence, DNA analysis was considered to be the most objective. Resting on complex chemical analysis, it seems stringently scientific – a gold-standard for how forensic science should be done. Yet perhaps juries should not be too quick to trust the DNA analyses they see in court.

Even trusted lines of evidence, such as fingerprint analysis, are not water-tight (Credit: Thinkstock)

In 2010, while working as a reporter for New Scientist magazine, I teamed up with Itiel Dror from University College London, and Greg Hampikian from Boise State University in Idaho, to put this idea of DNA’s objectivity to the test.

We took DNA evidence from a real-life case – a gang-rape in Georgia, US – and presented it to 17 experienced analysts working in the same accredited government lab in the US.

In the original case, two analysts from the Georgia Bureau of Investigation concluded that the man who was ultimately convicted of the crime, Kerry Robinson, "could not be excluded" from the crime scene sample, based on his DNA profile. But when the evidence was shown to our 17 analysts, they reached very different conclusions; just one analyst agreed that Robinson "cannot be excluded". Four analysts said the evidence was inconclusive and 12 said he could be excluded.

Yet just because forensic science is subjective, this doesn’t mean it should be disregarded; it can still yield vital clues that can help to catch and convict murderers, rapists, and other criminals. “Subjectivity isn’t a bad word,” says Dror. “It doesn’t mean that the evidence isn’t reliable, but it is open to bias and contextual influences.”

Blind judgement
What’s needed are additional safeguards to shield forensic examiners against irrelevant information that might skew their judgement. A first step is to ensure they aren’t given irrelevant information, such as knowing that witnesses have placed the suspect at the crime scene, or that he has previous convictions for similar crimes. Another safeguard is to reveal the relevant information sequentially – and only when it is needed. “We need to give them the information that they need to do their job when they need it, but not extra information that’s irrelevant to what they’re doing and which could influence their perception and judgement,” says Dror.

In the US at least, this is starting to happen: a national commission on forensic science has been established, with the goal of strengthening the field – and this includes looking at human factors like cognitive bias. But similar strategies are needed elsewhere if forensic science is to rebuild its tattered reputation.

When it comes to deduction and proof, there is still much we can learn from Arthur Conan Doyle’s hero. As Sherlock Holmes also once said: "Eliminate all other factors, and the one which remains must be the truth."

Hair is the western woman's veil

The west is fixated on Muslim veils, but all women's hair is bound in ideals of femininity, and a source of male judgment

• 
• • Arwa Mahdawi
  • theguardian.com, Friday 10 January 2014 15.23 GMT

'The time and money women spend on their hair isn’t just the free exercise of personal preferences, it’s part of a broader cultural performance.' Photograph: Ruslan Kudrin/Alamy

Packing for a winter holiday in The Muslim World can be tricky. Is the same outfit that dazzled a Shia fundamentalist in Iran going to be considered passé in Afghanistan? Does a classic black niqab work across all regions, or should you occasionally flash a little face?

These are all difficult questions. Luckily, however, the Pew Research Center has combined data visualisation with clip-art Orientalism to create a one-glance guide to female fashions in Muslim-majority countries. Pew has managed the impressive feat of reducing millions of women across markedly different regions down to just six stock "Muslim woman" cartoons. I don't want to oversimplify, but the overall conclusion from the visual is that some Muslims find faces acceptable, but most Muslims hate hair.

The Pew illustration is based on data from a wide-ranging survey conducted by the University of Michigan across seven predominately Muslim countries. While the survey looked at a number of topics, it is veiling that has been most seized upon by the press. As an article in Foreign Policy says: "Researchers investigated public perception of several hot-button issues … [but] one of their more interesting findings had to do with veiling."

Really? I mean, are veils really that interesting? As far as I can see the most interesting finding from the study is that it is yet another demonstration of the west's bizarre fixation on what Muslim women wear and how they cover their hair.

In part, this obsession seems to stem from the importance hair holds as a social and sexual signifier in non-Islamic countries. Back in 2001, Hillary Clinton gravely told the Yale College graduating class: "Your hair will send significant messages to those around you: what hopes and dreams you have for the world, but more, what hopes and dreams you have for your hair. Pay attention to your hair, because everyone else will.'' Clinton was being sarcastic. But in vitriol veritas: hair matters. Particularly if you're a woman.

Studies have found that the average woman in the UK spends £26,500 on her hair over her lifetime, with 25% of respondents saying they would rather spend money on their hair than food. And women don't just spend serious money on their hair, they spend serious time on it. On average, British women spend just under two years of their lives styling their hair at home or in salons.

Whether it's covered by a veil or coloured by Vidal Sassoon, hair is a feminist issue. Indeed, hair is so bound up with ideals of femininity that, to some degree, the measure of a woman is found in the length of her hair. In the semiotics of female sexuality, long hair is (hetero)sexual, short hair is non-sexual or homosexual, and no hair means you're either a victim or a freak. When Natalie Portman shaved her head for a film role she summed up these stereotypes with the observation that: "Some people will think I'm a neo-Nazi or that I have cancer or I'm a lesbian." But Portman also added: "It's quite liberating to have no hair."

Involuntarily losing your hair is an incredibly traumatic thing. When I was anorexic it was the fear of going bald that prompted me to get better, rather than, you know, the possibility of osteoporosis or infertility or death. Pulling out clumps of your hair is like pulling out clumps of your identity. But isn't it a little worrying that a bunch of dead cells on your head holds this much power? And isn't it odd that we should talk about chopping off our locks as "liberating?"

In a sense, women's hair in the west functions as it's own sort of veil, one which most of us are unconsciously donning. The time and money women spend on their hair isn't just the free exercise of personal preferences, it's part of a broader cultural performance of what it means to be a woman; one that has largely been directed by men. Rather than fixating on what the veil means for Muslim women, then, we should probably spend a little more time thinking about our own homegrown veils. Because it's still an unfortunate fact that, across the Muslim and non-Muslim world, women are often judged more by what is covering their head that what is in it. 

Vaginas may be weird and hairy, but they certainly don’t need steaming

We’ve moved on from stripping our most sensitive regions of their natural hair, and have
apparently started paying for vagina beauty treatments. Olivia Goldhill rounds up some of
the most absurd products imaginable, including the vajacial. Some women do this, but on their vaginas.  

By Olivia Goldhill
3:45PM GMT 05 Dec 2013

In the good old days, all you needed to be ready for sex is two willing participants and a healthy dose of sexual chemistry. Then pubic hair went out of fashion, and women suddenly had to start plucking, shaving, waxing,trimming away their natural state before copulation.
Now, it seems that vajacials are a thing. As in, facials, but for your vagina.

Apparently, these started off as a relatively simple affair in 2010, with a papaya enzyme mask, deep cleanse and tweezer hair extractions. They’ve moved on though. Impossibly, beauticians have moved on from convincing women that a papaya-scented nether region is a necessary aspect of good sex, and have introduced a whole new
range of vagina-themed beauty products.

Some women, before a big date or perhaps a romantic mini-break, actually book themselves in for a treatment of vaginal steaming. Presumably, they sit back, spread their legs and allow steam to gently (I hope) cleanse their vagina. But what temperature is the steam, where (exactly) does it go, and how on earth is steam any better at cleaning than plain water?
The treatments are usually done a day or two after the woman's period ends, and "heals any
imbalances" in the vagina. Which suggests I've been walking around with an unbalanced vagina for years.

Vaginoplasty is another trend, where you can shape your vagina into the desired shape. But what is this desired shape and who has a vagina that needs to be cosmetically re-modelled before sex? Poetry aside, vaginas are weird-looking things - they’re so un-pretty, I’m unsure what a “beautiful” vagina is supposed to look like. Perhaps we’ve been going overboard with the flower metaphors and some women actually want their vaginas to look like a rose.
Symmetry and neatness are listed as the longed-for traits, but this raises a whole new set of questions - is everyone else measuring their vaginas for perfect symmetry?

Now London’s getting in on America’s vaginal fashion trends, with salons offering "vaginal
rejuvenation" for hundreds of pounds. Bad news for students then (and most other people), who will undoubtedly struggle to afford an appropriately-preened vagina. Maybe it can be a special treat that a couple saves up for once a year, when they can enjoy annual sex day with properly presented sexual organs.

The vagina is apparently rejuvenated by a costly serum, which was originally created to treat wounds, but has moved on to a new life sprucing up female genitals. Magically, this serum can improve "vaginal function" and "tighten and firm the vaginal walls".

I’m not surprised that these treatments exist, but I’m a little scared that women—even one, solitary woman—is paying for them. There are women out there who are so anxious about what their partner will think about their vaginas, that they spend hundreds of pounds making them look “nice”.

But they need to stop this. They really do. No one envies the sex life of a woman complimented on her jojoba and rosemary scents. No one envies the sex life of a woman whose partner notices her jojoba and rosemary scents.

Vaginas are weird and they are hairy and that’s how they’re supposed to be. We need to stop worrying out what our poor vaginas look like during sex. It’s how they feel that really counts. OK?