How DNA evidence was potential banana skin

If it is anything more than pure myth, Lesley Thomson, QC, should have expected a routine few days in court, leading the prosecution in HM Advocate v Robert Leiper Graham.

As it turned out, she will have cause to remember one of her first High Court trials since taking the post of Solicitor-General for Scotland, second in command to the Lord Advocate in the hierarchy of Scotland’s prosecution service.

On the eve of the trial, the appeal court issued a judgment that decreed DNA evidence based on samples taken from a person after they had been charged was inadmissible. If a sample had not been taken during detention before charging, then it needed the permission of a court.

In a subsequent case affected by the ruling, the difficulty was overcome by the Crown applying for and being granted permission to take a new mouth swab from the accused.

Potentially, the Graham trial faced the same problem and would have caused Ms Thomson some sleepless hours. As it turned out, nothing was made of the point and the trial began on schedule.

That was not to say, however, that it would be all plain sailing in relation to the DNA evidence. After Ms Thomson had closed the Crown’s case, the defence counsel, Mhairi Richards, QC, caught her by surprise with a submission to the judge that Graham had no case to answer.

The challenge was along the lines that the prosecutor had not properly proved the DNA evidence and, without it, there was insufficient evidence against Graham, who should be acquitted.

Ms Thomson vehemently disputed that there had been any failings, but her blood pressure would have been done no favours by the judge, John Morris, QC, deciding that he wanted to consider the issue overnight.

Next morning, he ruled in favour of the Crown, and Ms Thomson would have been forgiven for heaving a sigh of relief.