Will DNA profiling fuel prejudice?

IT HAS revolutionised policing. In 10 years, the England and Wales National DNA Database (NDNAD) - the largest in the world - has matched nearly 600,000 suspects to crimes. This extraordinary success has been possible because police have unprecedented powers to retain samples from suspects, and other countries are following suit. But some experts argue that NDNAD's size and power mean it poses a serious threat to civil liberties.

One year on from legislation permitting police in England and Wales to collect and retain DNA samples from those arrested, a New Scientist investigation of the effect this is having on policing has revealed new data on the law's consequences.

Launched on 10 April 1995, NDNAD holds DNA profiles from almost 3 million people (see "DNA database: the facts"). "From an investigator's perspective it's a powerful tool," says Paul Stickler of Sussex police. In a typical month, the database churns out hits for 15 murders, 45 rapes and sexual offences and 2500 car, theft and drug crimes. With DNA evidence, the average crime clear-up rate increases from 24 per cent to 43 per cent.

And the database's scope is increasing, with police accruing more and more powers to collect and retain not just DNA profiles, but the biological samples themselves (see Timeline). In 2001, new legislation allowed the retention of profiles from suspects acquitted in court, and on 4 April last year police were given the authority to collect DNA from any person arrested on suspicion of a "recordable offence". These are people who may never have been charged, let alone convicted. Only in the state of California, whose voters passed "Proposition 69" last October to agree similar rules, will police have powers to retain DNA from all those arrested.

"It's the trend that we are concerned about," says Helen Wallace at GeneWatch UK in Buxton, Derbyshire. "There has been gradual expansion of the database without considerable public debate about where we draw the lines."

Similar trends are apparent in the US. In October 2004, the "Justice for All Act" allowed an expansion of the Combined DNA Index System (CODIS), the federal DNA database overseen by the FBI. CODIS was once reserved for those convicted of violent offences, but now states can upload profiles of almost anyone charged with a crime.

"We're seeing all sorts of function creep," says Tania Simoncelli at the American Civil Liberties Union in New York. "If your DNA is on the database it means that you are forever an automatic suspect for any crime in the future. It undermines the principle of presumptive innocence."
?In the end it comes down to prejudice as to who you think is going to be a criminal?

This may seem paranoid, but there are more tangible reasons to worry. Being listed could jeopardise employment or foreign travel, and the information could be used for research on topics such as the genetic correlates of ethnicity or criminal behaviour, for example. The UK's parliamentary science and technology committee agrees that there is insufficient ethical oversight for NDNAD. Last week it proposed the creation of an independent advisory board for the database.

The best argument for including innocent people's profiles on the database is, of course, that it gets results. Since it began in 2001, the practice of retaining profiles of suspects subsequently acquitted has added 175,000 extra profiles to the database. Of those, more than 7000 have since been connected with crimes, including 68 murders, 38 attempted murders and 116 rapes. No one can be sure how many of these suspects would have been caught by traditional detective work alone, but having their profiles on NDNAD has undoubtedly made policing easier. "These are serious offences that 'innocent' people committed. And they might not have been detected had their profiles not been retained," says Bob Bramley, former chief scientist at the UK's Forensic Science Service (FSS) and now custodian of the NDNAD.

And initial findings since the April 2004 rule change, show similar results. Gary Linton, a detective superintendent with Hampshire police, analysed data from 12 of the 43 police forces in England and Wales between June 2004 and January 2005. The results, revealed exclusively to New Scientist, show that 250 of these profiles have already been matched to crime scene samples, including four murders and three rapes.

One of the biggest bones of contention, though, is the retention of the original biological samples - most commonly cheek swabs or hair. Most of today's DNA profiles are based on short tandem repeats (STRs) - regions of non-coding "junk" DNA that contain short repeated DNA motifs a few letters long. The number of repeats at each site identifies an individual with extremely high reliability. STR profiles were devised to reveal nothing more about a person than their identity. But full DNA samples hold every scrap of genetic information, which can reveal all sorts of details, such as propensity to develop genetic diseases, eye colour or ethnicity.

The FSS says it keeps physical samples to correct mistakes in the database. If a profile match is in doubt, investigators can go back to the original sample to double check. Having the original source also means that forensic scientists can refine a profile to include more STR locations - thereby decreasing the likelihood of a false match.

Bramley says the FSS has no plans to use the physical samples to carry out research on retrieving non-STR data. But some in the FSS do have their eye on extracting more information from physical samples. Danesh Kara, a researcher who works on NDNAD, says that samples collected now could be subjected to future techniques, such as gleaning a person's likely physical characteristics or ethnicity from a crime scene sample (New Scientist, 20 July 2002, p 34). "The physical sample is kept because we believe that in the future the technology will improve," says Kara.

Using the database for research is extremely contentious, though. "As a geneticist I would greatly value the potential enormous power of the database for research," says Alec Jeffreys, who invented DNA fingerprinting. "But it's a gross infringement of civil liberties." Nonetheless, the database has already been used for research. The Home Office and NDNAD custodian have authorised 10 research projects since 1995, including one study on extracting statistical information on ethnicity from STR profiles. "Most of the research has been done by the FSS itself, but there are no guarantees that it will be limited as such in the future," says Wallace.

And while physical information such as hair and skin colour could be useful for policing purposes, some worry this could mean the database will be used in a highly discriminatory fashion. "Because there are more samples from minorities, the police are just more likely to look to these communities," says Dominic Bascombe, a journalist at the London-based black community newspaper The Voice. "And in the end it does come down to prejudice as to who you think is going to be a criminal."

One answer would be to put everyone on the database. But for David Lazer at Harvard University, who has studied the ethical issues raised by DNA data, the question is quite simple. "Would you want J. Edgar Hoover to have his hands on everyone's DNA?"