Justice system's worst nightmare

It is the justice system's worst nightmare - a lengthy trial, a string of expensive counsel and solicitors and costs running into hundreds of thousands of pounds.

The unenviable decision over whether to embark on an equally lengthy and costly retrial now falls to Barbara Mills QC, Director of Public Prosecutions.

She is expected to consult the Sir Nicholas Lyell QC, the Attorney General, whose consent had to be sought for the prosecution in the first place because it was being brought under the Prevention of Corruption Act. But the final decision is hers.

The tests for whether a prosecution should be brought are whether there is enough evidence to support a realistic prospect of conviction, and whether the trial would be in the public interest. The fact that a jury has failed to agree once on a body of evidence dictates that decisions to press ahead are taken only after careful consideration.

There is nothing to stop the Crown from running the second trial in a different way, but the chances of finding additional evidence are usually slim.

In high-profile cases, the fact that the issues have been publicly aired may also be a reason for concluding that the public interest would not be served by rehearsing them again.

Recent cases where juries were unable to agree include that of showjumper Harvey Smith. Juries twice could not reach a verdict over an assault charge relating to a dispute over a golf course border, and he was cleared.