Single typing error lets accused teenager off the hook for alleged head-stamping assault.

Chae MacDonald, 17, faced charges, mainly motoring offences, and prosecutors wrote to his lawyer saying they would be prepared to accept guilty pleas to only some of them. However, a mistake was made in numbering and the assault was not included in the list of charges which the Crown wanted to keep.

Yesterday, three appeal judges ruled the Crown was bound by the letter, freeing MacDonald, of Dancing Cairns Crescent, Aberdeen, from the assault charge.

The Justiciary Appeal Court in Edinburgh had heard that the system of "acceptable plea letters" was introduced in sheriff courts two years ago to help reduce inconvenience to witnesses and victims, and that this was the first report of an error.

MacDonald was accused of six charges, all said to have been committed on 18 July last year. Five related to a motorcycle accident in Aberdeen, and were of careless driving, having no licence or insurance, failing to stop, and not wearing a helmet. In the sixth, it was alleged he acted with another man and assaulted William Forrester by punching him and stamping on his head.

Because the Crown had decided to prosecute MacDonald in Aberdeen Sheriff Court by summary procedure, he faced a maximum sentence of a few months' detention.

The depute procurator-fiscal handling his case wrote to MacDonald's solicitor saying the Crown would be prepared to accept guilty pleas to charges 1, 2, 3 and 4. The letter should have stated 1,2, 3 and 6. When MacDonald pleaded guilty to charges 1-4, the Crown rejected the offer. The defence argued the Crown was bound by the letter, but Sheriff David Hall ruled MacDonald could still be prosecuted for the assault.

The issue then went before the appeal judges, Lords Clarke, Hardie and Marnoch. Delivering yesterday's judgment, Lord Hardie said "acceptable plea letters" had been a response by the Lord Advocate, Elish Angiolini, QC, to concerns that around 16,000 cases a year had witnesses called, but the accused pleaded guilty.

"If such letters are to achieve their objective of encouraging resolution of a case at the earliest opportunity, it is essential that solicitors can have the confidence to rely upon their terms," said Lord Hardie.

"If letters cannot be relied upon, solicitors cannot be expected to give appropriate advice to clients. The benefit to the public interest will be lost.

"If the Crown is bound by the terms of such letters, the only disadvantage is that an accused might occasionally benefit from an error. It seems to us significant that this is the only reported case of an error."

MacDonald's case was sent back for sentences to be imposed for the four motoring offences.