DNA retention by police

What is DNA?

DNA stands for deoxyribonucleic acid, the chemical that carries the genetic code for all human life.

The study of DNA is important not only for increasing medical knowledge, but also for forensic purposes:

  • because each individual’s DNA is both highly complex and unique to that person (or, at the very least, shared only by identical twins), DNA is the most powerful form of identification available,
  • since DNA is found in every human cell, it is possible to gain a sample of someone’s DNA by a wide range of means: a strand of hair, a flake of skin, a mouth swab containing saliva, or a blood sample, etc. Although it is relatively easy to avoid leaving fingerprints at a crime scene, for example by wearing gloves, it is often much harder to avoid leaving DNA evidence.

Since 1985, when Sir Alec Jeffreys at the University of Leicester pioneered the development of DNA profiling, it has been possible for forensic experts to use DNA to match suspects with genetic samples taken from crime scenes. Accordingly, DNA has become an immensely powerful forensic tool in the investigation of crime.

What powers do the police have to take a DNA sample?

It has always been open to a person to volunteer a sample of their DNA for identification purposes, eg to allow them to be eliminated as a suspect in police investigations.

The source of the police power to take DNA samples from individuals in custody originates in section 63A of the Police and Criminal Evidence Act 1984. However, until the Criminal Justice and Police Act 2001, it was unlawful for the police to retain those samples where an individual was subsequently acquitted or the charges discontinued. The 2001 Act allowed police to retain DNA samples of persons charged with offences, even after their acquittal. However, such samples could only be used subsequently by the police ‘for purposes related to the prevention or detection of crime, the investigation of an offence or the conduct of a prosecution’.

Under the Criminal Justice Act 2003, the police now have the power to take and retain a DNA sample of any person arrested for any recordable offence, regardless of whether they are even charged or, if charged, subsequently acquitted.

This has led to the establishment and development of the National DNA Database (NDNAD, also known as the National Criminal Intelligence DNA Database), which now has DNA samples from more than 3.5 million people, including over half a million samples from children under the age of 16. There are also concerns that persons from ethnic minorities are disproportionately represented in the numbers of DNA samples held. Given the extensive powers that the police have to take and retain DNA samples from suspects (and former suspects), the NDNAD has become the largest forensic DNA database in the world.

Why is DNA retention a human rights issue?

Because each DNA sample contains massive amounts of personal information about an individual. Accordingly, the retention of DNA samples raises major implications for the protection of individual privacy, particularly the confidentiality of medical information.

With traditional forms of biometric identification, such as fingerprints, retention does not raise significant privacy concerns. This is because fingerprints are virtually useless for anything else besides identification.

By contrast, retaining a sample of a person’s DNA means that the holder of the sample could use it to uncover a very broad range of potentially intimate medical and genetic information about that person, eg whether they carry the genetic marker for diseases such as Parkinson’s, or their susceptibility to heart disease. Indeed, because medical knowledge of the human genetic code is constantly expanding, it is not yet known the full extent of information that may be obtained from a DNA sample.

The police, however, maintain that access to and use of DNA samples stored for the purposes of the database is strictly regulated and attended by stringent safeguards.

Has anyone challenged the police retention of DNA samples?

Yes. In R v Chief Constable of South Yorkshire Police ex parte S and Marper(([2004] UKHL 3)) the House of Lords heard a challenge from two individuals who had been arrested and had DNA samples taken. Following the 2001 Act, their samples were kept on the database even though they were never convicted of any criminal offence.

The appellants in Marper argued that, although retention of a DNA sample could be justified where a person had been convicted of a serious criminal offence (and could arguably be considered a suspect in the investigation of future offences), the policy of retaining DNA samples of those who had not been convicted was an unjustified and disproportionate interference with their right to respect for their private life under Article 8 ECHR.

Unfortunately, the Law Lords rejected the challenge on the basis that mere retention of a person’s samples did not constitute an interference with the right to privacy under Article 8. This was an especially surprising conclusion, given the increasing potential for other government bodies and, indeed, other law enforcement agencies throughout the EU to gain access to the database. The very knowledge that someone else holds highly personal information about you – however strong the safeguards against its misuse – seems an obvious interference with privacy, even if the interference can ultimately be justified on other grounds. The matter is now on appeal to the European Court of Human Rights.