The scales of justice are tipped against defendants

The existing rules against double jeopardy - trying a suspect twice for the same crime - can give considerable cause for queasiness. There have been notable cases where a jury has acquitted someone, only for the person who has been acquitted to boast of his crimes or for DNA evidence to make clear that he or she was indeed guilty. Each guilty murderer allowed to walk the streets freely undermines the judicial system.

The existing rules against double jeopardy - trying a suspect twice for the same crime - can give considerable cause for queasiness. There have been notable cases where a jury has acquitted someone, only for the person who has been acquitted to boast of his crimes or for DNA evidence to make clear that he or she was indeed guilty. Each guilty murderer allowed to walk the streets freely undermines the judicial system.

None the less, yesterday's recommendation by the Law Commission to abolish the double-jeopardy principle should make us feel queasier still. Admittedly, the abolition of the double-jeopardy rule would apply only if there is clear new evidence - not, in the deadpan phrase of the commission, "where the acquittal was perhaps surprising". (Translation: "where the jury took leave of its senses.") Even with that proviso, however, it is still inappropriate to change the rules.

The most important objection is not the point of principle in changing a law that has served us well since the time of Magna Carta. Ancient laws have been changed or abolished many times over the years, and that process will continue.

Crucially, however, the abolition of the double-jeopardy rule strikes at the very heart of the jury system. Under the current system, a man or woman who has been acquitted should remain free of all stigma. Lord Denning notoriously questioned this principle, wrongly declaring that, though the Guildford Four were acquitted on appeal, they were "probably guilty". But even Denning apologised for his foolishness. It would be wrong if the stigma - including questions about a person's guilt - were allowed to linger on, even after a jury acquittal. The retrial would stack the dice against the defendant to an extraordinary degree, since a jury would be liable to perceive the very fact of a retrial as a clear-cut indication of guilt.

These new proposals are not even the thin end of the wedge; the wedge is already far too thick. Already, the rights of defendants have been chipped away by successive governments - including the right to silence and the automatic right to trial by jury. This latest change would set a dangerous precedent and would turn on its head the principle of innocent until proved guilty, so that anyone could be regarded as guilty even after being found innocent in a court of law. Even now, the Government can ignore the commission's proposals. In the interests of justice, it should do so.