DNA evidence


DNA stands for "deoxyribunucleic acid" and it is the blueprint for your genetic makeup. DNA is composed of a pattern of bands (a little like a bar code) and the arrangement of the bands is unique to every person. There are some common features between the pattern of bands of parents, their children and other relatives.

DNA testing

DNA testing can be done on a tiny sample of blood, semen or any body tissue. When a DNA test is done, a "profile" of the DNA is taken. DNA testing can be very useful evidence, for example:

  • DNA can be used to establish paternity. If your DNA is compared to another person's, it can be established whether you are the parent of that person.
  • DNA can also be used to prove identity. For example, if a sample of blood is found at the scene of the crime, a DNA test can be performed on that blood to work out the DNA "profile". That DNA "profile" can then be compared to a suspect's DNA sample. That way, it can be established whether the blood found at the scene of the crime is the suspect's blood.

The Criminal Justice Act 2006 provides that mouth swabs and hair samples will no longer be considered as "intimate samples" , this means that your consent is not required for taking them.


When DNA evidence is introduced in court, it is always explained by an expert witness. The expert will tell the court how often that "profile" is found in the general population. For example, the expert may tell the court that this "profile" is found in approximately 1 person in every 1,000,000 people.

Criminal Law and Procedure: Establishment of a DNA Database

The Law Reform Commission of Ireland published a Consultation Paper on the Establishment of a DNA Database in March 2004. The publication of this Consultation Paper followed a request in 2003 by the Ireland's Attorney General to consider the issue. Recommendations made by the Commission examined the broad and complex constitutional and human rights issues that may arise; and secondly, the more specific question of what classes of DNA profiles would make up any database.

The Law Reform Commission Paper drew clear distinctions between DNA samples and DNA profiles in making its recommendations, concluding that profiles only would be retained on the database. The Commission made a provisional recommendation on the establishment of a limited DNA Database, in which profiles of those reasonably suspected of, and convicted of, serious crimes would be retained on the database.

The Consultation Paper also addressed the issue of who should regulate and maintain the DNA Database, recommending that an independent State Forensic Agency be established for this purpose. The Law Reform Commission published their final Report on the Establishment of a DNA Database (pdf) in November, 2005.

In June 2014 the Oireachtas passed the Criminal Justice (Forensic Evidence and DNA Database System) Act 2014 (pdf).

Further information

For more detailed information you should seek legal advice.

Page edited: 14 July 2014