Australasian Science Magazine

Over-reliance on DNA profiles in crime investigation is just one facet of a growing acceptance of genetic determinism – the assumption that we are our DNA. Credit: Jamie Tufrey

By Michael Cook

When the DNA profiles of innocent people are kept by law enforcement agencies it places them at risk of a lifetime of genetic surveillance.

One of the longest-running TV shows in the US is America’s Most Wanted, a reality show that gets viewers to dob in murderers, rapists and child molesters. To date, it claims to have fingered 1110 criminals.

Such is its popularity that in March host John Walsh celebrated the 1000th episode at the White House. President Obama used to be a law lecturer, but it didn’t take much arm-twisting to get his personal backing to taking and retaining DNA samples from individuals arrested for a crime but not convicted. “No different than fingerprinting or a booking photo,” said Walsh, and Obama nodded sagely and replied: "It's the right thing to do".

But is it? Experts on human rights say no.

The European Court of Human Rights may have slowed down Britain’s rapid move to almost-universal DNA profiling. In a 2008 judgement it found that indefinite retention of DNA samples from everyone who is arrested, regardless of their age or guilt, was a violation of a basic right to privacy.

The database in the UK includes more than five million DNA profiles, and one-fifth of these come from people without a criminal record. However, the government has been reluctant to destroy profiles because police and the public feel that DNA records are vital to putting criminals behind bars. The argument is that if you’re not a crim, you’ve got nothing to worry about.

Apart from privacy concerns, many experts worry that the technology for forensic investigation is far from perfect. Here in Australia, Victorian police were forced to suspend the use of DNA evidence for a month last year after a substantial miscarriage of justice. A 20-year-old, Fara Jama, spent 18 months in jail for a rape he didn’t commit. It turned out that DNA taken from him 24 hours before the crime over an unrelated offence for which he had not even been charged had contaminated the crime scene evidence.

How could that ever happen? Lawyers attribute it to the “white coat syndrome” – the power of shuffling statistics and graphs and figures before a mesmerised audience. Colin Powell did it to the United Nations when he used high-resolution images to “prove” that Saddam Hussein had weapons of mass destruction. And ordinary juries are no less susceptible to the allure of exact numbers and scientific precision.

A recent study by the Australian Institute of Criminology reported that juries are 23 times more likely to bring in a guilty verdict in murder cases if there is DNA evidence, and 33 times more likely in rape cases. There is a lot of concern that jurors, in the words of one judge, can be “overawed by the scientific garb in which the evidence is presented, and attach greater weight to it than it is capable of bearing”.

Like mathematics, science is logical. But unlike mathematics, the results of scientific work have to be filtered through instruments and technicians and interpreted by experts. There is abundant room for unexpected error.

Erin Murphy, a legal academic at Berkeley, summed up concerns in a recent article: “Even DNA typing – the archetypal objective science – requires an analyst to make judgment calls separating signal from noise. Just because a discipline is founded in scientific principle does not mean that it always yields wholly determinate answers: there is meterology and there is math.”

In fact, as pointed out recently in the Los Angeles Times by Osagie K. Obasogie of the Center for Genetics and Society in California, DNA testing is still an art as much as a science. Even though everyone’s DNA is unique, current tests still have a surprising margin for error. “The entire enterprise of DNA databases is based on the idea that no two people share the same profile. But Arizona's database of 65,000-plus entries was shown to have more than 100 profiles that were similar enough for many experts to consider them a ‘match’," he wrote.

Over-reliance on DNA profiles in crime investigation is just one facet of a growing acceptance of genetic determinism – the assumption that we are our DNA. More sophisticated techniques and protocols may eventually iron out the wrinkles with forensic evidence. But we can expect other important human rights debates as governments come to rely more and more upon genetic profiling for health care delivery, identification and security systems.

President Obama was extremely unwise to endorse a government database that could place citizens at risk of a lifetime of genetic surveillance.