With good reason. It has ensured that an individual who had “tholed his assize” or stood trial was not subjected to continued harassment by the state and, in demon­strating that a jury’s verdict is final, has contributed to public confidence in the legal system.

Yet that confidence is undermined if someone who has been tried and acquitted subsequently confesses to the crime or if compelling new evidence later comes to light, with no possibility of a retrial.

Whether that should be changed was one of several issues raised as a result of disquiet following the abrupt

ending of a murder trial in 2007 when the judge ruled the DNA evidence was insufficient for the jury to reach a verdict.

After an examination

prompted by that case, the Scottish Law Commission (SLC) conclusion – that the double jeopardy rule remains essential to the rule of law but needs to be clarified – is too cautious for many politicians. However, its recommendation that the rule should not apply if someone who has been acquitted later admits carrying out the offence, or if the original trial was corrupted – for example, by intimidation of witnesses or jury-rigging – is a significant acknowledgment that such cases seriously offend our idea of justice and undermine public confidence in the criminal justice system.

The commission recommended that any change in the law should not be retrospective. That might result in disappointment that a retrial of Angus Sinclair for the murder of two 17-year-old girls (the case which triggered the review) will not be possible. However, knee-jerk reactions to individual cases can never be the only basis for changing legislation and all accused people should be subject to the law as it stood at the time of their trial.

The most obvious omission from the SLC’s recommendation is the possibility of a retrial when new evidence (other than confession) comes to light.

Most people believe that the prospect of further scientific and technical advantages should at least allow consideration of a further trial if the new

evidence is compelling.

The exceptions to double jeopardy, however, must be just that: rare cases that do not conform to the general rule. The evidence from England and Wales, which amended double jeopardy legislation in relation to murder in 2005, suggests that will be the case. Since the Act came into force, there have been only six applications for a retrial, with three accepted, two of them as a result of an admission by the person originally acquitted.

Discerning “a clear direction of travel”, Kenny MacAskill, the Scottish Justice Secretary, has declared he will legislate for change at the earliest practical opportunity. He is right to do so. However, his undertaking that Scotland’s approach to double jeopardy should reflect the interests of justice and not just the accused must be pursued with care. It must not erode the principle that every­one is innocent until proven guilty. It is an essential tenet of our justice system, as is its corollary that someone found not guilty cannot be repeatedly tried until the prosecution proves its case.