S and Marper: Will the Police Delete your DNA?

After the  historic ruling at the ECHR  for S and Marper v United Kingdom, there is an expectation that the police will be forced to delete all of the DNA collected and retained from  innocent people.

While they [the Police] probably should delete the DNA samples collected from people who were never charged or found not guilty, there is no major announcement from the Home Office to that effect.

In fact, even if the UK creates a new law, based on this test case stating that Police cannot retain DNA from the innocent/non convicted people they may still not delete the data,  for a simple reason – there is no deterrent to keeping it, even if retaining the DNA is illegal.

In US Law there is the concept of “fruit of the poisoned tree”. This means that not only is evidence collected illegally inadmissible it also  means that all evidence found from that information is also inadmissible. For example if a search is illegal, and the search reveals evidence that proves a case, that evidence will not be accepted.

In the UK this is not the case, in fact there are specific laws addressing just this question.

Section 78 of PACE allows the courts to exclude information if it is has been collected illegally, but it does not require it. In fact there are several cases where data that has been collected illegally, has been allowed. Section 76 of PACE deals with similar issues, but in relation to coerced confessions.

Therefore if the police retained the DNA evidence, rather than deleting it it, and then used the DNA sample to locate somebody then that conviction would probably stand, i.e. there is no deterrent to reatining, illegally,  the DNA samples held.

In fact there is case law to support this exact case.


In 1990s when the DNA collection laws where first created the police could only collect DNA after charging, and then had to delete the sample if the individual was found not guilty. This was prior to the laws changing in 2001 and 2004, which allowed the police to take DNA prior to charging and retain it even if the person was not guilty. It is this change in the law that led to the  S and Marper case.

In 1997, when the original DNA collection laws were in place, a male committed a particularly horrific rape of on a 66 year old woman. The offender was detected via a DNA sample left at the scene,  which was matched against the National DNA database. The offender was arrested and  new DNA sample taken (as there always is), and the DNA match confirmed. This DNA evidence resulted in the conviction of the offender. However, the defence team appealed this as the original DNA sample, which led to the arrest was obtained from crime he was not convicted of, and as such should have been deleted.

This argument was initially won, in the Court of Appeal, but was then referred to the House of Lords, at which point the House of Lords stated the DNA sample should have been allowed to be used. As the House of Lords is the superior court this means that the DNA samples that have been kept or obtained illegally can be used to detect offenders.

Therefore it is entirely possible that the following occurs:

The S and Marper case directs the UK to not collect more DNA samples prior to charging, and that those DNA samples of of innocent people that are retained should be deleted. But, the police do not delete the samples and continue to use them as evidence.

Will the police delete your DNA? Probably not.


5 Responses to “S and Marper: Will the Police Delete your DNA?”

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