By Helen Wallace

The collection, use and storage of DNA for forensic purposes have increased rapidly since 1995, when the world's first DNA database was set up in Britain. The use of DNA in criminal investigations can undoubtedly be highly beneficial, providing evidence that can help to convict the guilty and exonerate the innocent.  However, the retention of individuals' DNA profiles and other information on computer databases, combined in some countries with the storage of linked biological samples, raises many privacy and individual rights issues. These include potential misuse of the information by governments or others and the prospect that false DNA matches may lead to intrusive investigations of innocent people by law enforcement agencies.

This paper discusses the evidence and reasons that innocent people whose DNA profiles are contained in DNA databases may be vulnerable to stigmatization or prejudicial treatment. It draws on experiences from the development and operation of the National DNA Database in Britain, which contains the largest proportion of the population of any DNA database in the world.

Both DNA and fingerprints may be left wherever a person goes. The retention of an individual's DNA profiles and fingerprints in a database therefore allows a form of biological tagging or 'biosurveillance' which can be used to establish whether a person has been present at a particular location.1 This purpose goes beyond mere 'identification' to mapping an individual's movements, including (but not limited to) using biological evidence to establish their likely presence at a crime scene.

Unlike fingerprints, DNA can also be used to investigate biological relationships between individuals (including paternity and non-paternity), and thus trace other individuals who may be related to a person whose DNA profile has been obtained from a crime scene or elsewhere. Biological relationships can be statistically inferred from computerised DNA profiles by searching for partial matches between profiles (an indication of relatedness), a process known as 'familial searching'.

The computerized DNA profiles held in DNA databases are a string of numbers based on specific areas of each individual's DNA, known as short tandem repeats. However, some countries also retain the biological samples collected from individuals, linked to their record on the computer database by a reference number. A person's DNA sample contains additional private information about their health and other physical characteristics. Some of this information (such as carrier status for a genetic disorder) may be highly sensitive and/or unknown to the individual.

The National DNA Database (NDNAD) in Britain was the first to be established and contains a much larger proportion of the population than any other country in the world. An estimated 576,250 individuals had records added to the Database in 2006/07: one person every minute.2 About 4.2 million people - nearly 7% of the population - had their DNA profiles retained on the Database by the end of October 2007.3 Approximately 1 million of these individuals have never been convicted or cautioned for any crime. Many countries are considering establishing or expanding their databases in line with the changes made in Britain, and examination of the NDNAD therefore provides an opportunity to consider the potential for stigmatization or prejudicial treatment of individuals with records on the Database.

Uses of the NDNAD may include any purpose "related to the prevention or detection of crime." Uses now include familial searching (using partial DNA matches to try to identify the relatives of a suspect), searching by name, and undertaking various types of genetic research (including controversial attempts to predict ethnic appearance from DNA).4

GeneWatch UK recognizes the extremely important role that DNA can play in some criminal investigations. We are not opposed to the existence of the National DNA Database, but are deeply concerned that its rapid expansion is spiraling out of control. The law in England, Wales and Northern Ireland allows the capture and use of genetic information without consent from a defined section of the community (those who have been arrested for a recordable offense), often referred to as the 'active criminal population,' despite the fact that many of these individuals will not have committed any crime.

 Table 1: Estimated numbers of individuals on the NDNAD at end June 2006.


Original PQ*


Unconvicted persons with a PNC record



Persons who have received non-custodial sentences or cautions, recorded on the PNC

1,681, 284

1,681, 284

Persons who have had a custodial sentence, recorded on the PNC



Estimated total no. individuals on NDNAD with a PNC record



Estimated total no. of individuals on NDNAD with no PNC record (includes 18,056 volunteers).***



Estimated number of individuals with profiles on the NDNAD



Estimated number of replicate profiles



Total number of individuals' DNA profiles on the NDNAD



* Assuming the 11% replication rate then in use.
**Assuming the 13.7% replication rate now in use.

There is a strong bias in the system towards the inclusion of DNA profiles from young black men and vulnerable people, including children and the mentally ill.

The rapid expansion of the Database has enormous implications for the balance between the power of the state to implement 'biosurveillance' on an individual and the individual's right to privacy. There is also significant potential for others - including organised criminals - to infiltrate the system and abuse it, for example by using it to reveal changed identities and breach witness protection schemes.

The permanent retention of all DNA profiles, samples and police records significantly changes the relationship between the individual and the state. Individuals with records on the DNA Database lose their presumed legitimacy to go about their daily life, their right to refuse to take part in genetic research and their right to keep their family relationships and other genetic information private. Even if they have never been charged or convicted of any offence, they may be refused employment or a visa as a result of the retention of a permanent record of their arrest on the Police National Computer. The retention of an individual's DNA profile also allows their movements to be tracked or their relatives to be identified. The potential implications for the right to protest are particularly serious.

There are many circumstances in which the retention of an individual's DNA profile and linked data will give rise to potential identification, but in the majority of cases this does not involve the identification of the individual as the perpetrator of a crime. Many individuals identified through matches on the Database will be subject to investigation by the police but are subsequently acquitted of any crime. The purpose of data retention is quite different from the purpose of collection; retention of DNA data is a form of surveillance based on the idea that the individual, or a relative of theirs, may commit a future crime. Records and samples can also be used without consent for a much broader range of purposes than those for which they were originally collected, such as inclusion in genetic research.

It is difficult to reconcile the current situation with the principle of equal application of the law (the concept that everyone is equal before the law).

People on the Database are treated as members of a 'risky population' whose DNA requires permanent retention by the state.5 Youths, people suffering from mental illness, and people from black and minority ethnic groups are particularly likely to be members of this 'risky population.'

Approximately 27% of the entire black population, 42% of the male black population, 77% of young black men, and 9% of all Asians have records on the National DNA Database, compared with just 6% of the white population.6 The rate of arrest of 10-17-year-olds has also risen disproportionately as the result of new arrest targets set for the police: between 2002-06 arrests of children and young people rose by 16.4%.7 Retention of an individual's DNA profiles on a Database is likely to be of most benefit when he or she has a record as a 'career criminal' and is considered likely to re-offend. However, the population on the Database now includes anyone who is arrested for a recordable offence. Ministers have accepted that: "As far as we are aware, there is no definitive data available on whether persons arrested but not proceeded against are more likely to offend than the population at large."8

The lesson from the rapid expansion of the National DNA Database is that there is significant potential for stigma and prejudicial treatment of people who have their DNA profiles retained. Although putting everyone on the Database is sometimes proposed as a solution to discrimination, it would not prevent the Database from being used in a discriminatory way and would considerably exacerbate concerns about potential misuse and false matches. Such proposals are also widely regarded as extremely costly and impractical.

The rapid expansion of the National DNA Database has not improved the crime detection rate. Since 2002/03, the number of individuals with DNA profiles on the Database has more than doubled from 2 million to 4.5 million, but there has been no corresponding increase in the number of crimes detected using DNA.9 An earlier increase in DNA detections was due to the decision to take more DNA from volume crime scenes (particularly thefts and burglaries), not to putting more individuals on the Database.10

Table 2: Predicted adventitious DNA matches using full profiles on the NDNAD








No. on database (millions)







No. of case stains (thousands)







Expected mean no. of adventitious matches







Source: Gill P (2008) National DNA Databases and some other deliberations. Presentation to the Foundation for Science and Technology. 6 February 2008.


GeneWatch UK believes that there are important changes that could be made to improve safeguards for human rights and privacy without compromising the role of the DNA Database in tackling crime. A better balance would be struck by:

1. Reintroducing a system of time limits on how long people are kept on the Database - so that only DNA profiles from people convicted of serious violent or sexual offenses are kept permanently.
2. Destroying all individuals' DNA samples once an investigation is complete, after the DNA profiles used for identification have been obtained.
3. Ending the practice of allowing genetic research using the Database or samples, limiting permissible research to performance management and database improvements.
4. Better governance of the Database, including an independent regulator.
5. Public and parliamentary debate before new uses of the Database are introduced.
6. A return to taking DNA on charge rather than arrest, except where it is needed to investigate a specific offense.

Helen Wallace is Director of GeneWatch UK, a not-for-profit science policy research group which aims to ensure that genetics is used in the public interest. She has been Director since January 2007, and was Deputy Director from September 2001, with overall responsibility for GeneWatch UK's work on human genetics. The focus of her work at GeneWatch has been on the assessment and regulation of genetic tests and genetic databases, including the genetic research project UK Biobank and the police National DNA Database.



1. Williams R, Johnson P (2004) Circuits of surveillance. Surveill Soc, 2(1), 1-14.

2. Parliamentary Question. House of Commons Hansard. 30 Oct 2007 : Column 1254W.

3. Parliamentary Question. House of Commons Hansard. 7 Jan 2007:  Column 274W.

4. GeneWatch UK(2006) Using the police National DNA Database - under adequate control? GeneWatch Briefing. June 2006. Available on:

5. McCartney C (2004) Forensic DNA sampling and the England and Wales National DNA Database: a sceptical approach. Critical Criminology, 12, 157-178.

6. National DNA Database. Adjournment Debate. House of Commons Hansard 29 Feb 2008 : Column 1427.

7. Home Office Statistical Bulletins: 'Arrests for Recorded Crime etc.' 02/03-05/06

8. House of Commons Hansard 9 Oct 2006: Column 491W

9. Crimes solved by DNA evidence fall despite millions being added to database. The Telegraph. Available on: .

10. Home Office (2006) DNA Expansion Programme 2000-2005: Reporting achievement. Forensic Science and Pathology Unit.
Search: GeneWatch
For centuries, human societies have divided population groups into separate races. While there is no scientific basis for this, people unquestioningly accept these classifications as fact.
View Project
The Gene Myths series features incisive, succinct articles by leading scientists disputing the exaggerations and misrepresentations of the power of genes.
View Project