Can DNA found on drugs be used as evidence in court or is that unconstitutional? DNA can be transferred from different sources so it doesn't necessarily mean the DNA holder has come in direct contact with the drugs, correct?

  • Also see Willow Martin Charged in Arson. Apparently the couple burned down the business and stuffed a potato in a company van tailpipe. The DNA on the potato led to a registered offended, who was the boyfriend of the female arsonist. (The stripper burned down the business of the father of another stripper).
    – jww
    Commented Sep 20, 2018 at 20:38

1 Answer 1


Yes, DNA found on drugs could be used as evidence in court, although, by itself, it might not be sufficient to support a conviction.

Generally speaking, otherwise duly authenticated physical evidence is admissible when it is "relevant" and it is is "relevant" when it makes it more likely that an element of the crime (in this case, possession) is true than would be the case in the absence of this evidence. There are specific exceptions that disallow the introduction of relevant evidence, the most general of which is that it would be unduly prejudicial to admit the evidence which is otherwise of only marginal relevance, but in practice, I think that the DNA evidence would pass this test.

It is more likely that someone whose DNA is found on drugs had something to do with the drugs than if their DNA was not on the drugs, even if it isn't absolutely certain that the person was actually in possession of them, so it would be admissible.

  • Let me give you an example. I had a roommate in university who heavily smoked marijuana. We had a spat near the end of the term before we moved out and to get back at me he took some of my DNA (skin cells, saliva, hair cells, etc.) from the bathroom and put it into a plastic bag, contaminating the marijuana with it and left it there to be found. Can the police convict me for possession because my DNA was on/around it? Could it be defensible to say that DNA can be moved around objects without direct contact so DNA alone isn't enough to prove that I was actually in possession at any given time?
    – ATomz
    Commented Aug 25, 2017 at 20:34
  • 1
    @ATomz: you seem to be confused about 'evidence' and 'conviction'. The police can (subject to the prosecutor) charge you with possession of drugs, and offer in evidence the DNA. That is unlikely to be enough to convict you, but it is up to the court (presumably a jury given directions about the law by a judge). Commented Aug 25, 2017 at 21:28

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