<P> The United States Supreme Court ruled in Maryland v. King (2013) that DNA sampling of prisoners arrested for serious crimes is constitutional . </P> <P> In the UK, the Human Tissue Act 2004 prohibits private individuals from covertly collecting biological samples (hair, fingernails, etc .) for DNA analysis, but exempts medical and criminal investigations from the prohibition . </P> <P> Evidence from an expert who has compared DNA samples must be accompanied by evidence as to the sources of the samples and the procedures for obtaining the DNA profiles . The judge must ensure that the jury must understand the significance of DNA matches and mismatches in the profiles . The judge must also ensure that the jury does not confuse the match probability (the probability that a person that is chosen at random has a matching DNA profile to the sample from the scene) with the probability that a person with matching DNA committed the crime . In 1996 R v. Doheny Phillips LJ gave this example of a summing up, which should be carefully tailored to the particular facts in each case: </P> <P> Members of the Jury, if you accept the scientific evidence called by the Crown, this indicates that there are probably only four or five white males in the United Kingdom from whom that semen stain could have come . The Defendant is one of them . If that is the position, the decision you have to reach, on all the evidence, is whether you are sure that it was the Defendant who left that stain or whether it is possible that it was one of that other small group of men who share the same DNA characteristics . </P>

When was dna first used to solve a crime