THE pursuit of justice can be fraught with difficulties. Even the best constructed prosecutions depend on witnesses being prepared to testify to the same facts in court as they have previously set out in statements to the police and to their lawyers. Sadly, some witnesses change their minds. If these so-called 'hostile' witnesses refuse to co-operate or claim to have forgotten the facts, a case built on their testimony is bound to collapse. Short of trying them for perjury - an offence notoriously difficult to prove - there is precious little the prosecution can do about it.
Nevertheless, there may be ways to make it harder for a witness to claim to have forgotten the events on which the original statement was based.
One possibility, albeit of little help in a case where the witness claims mental illness or amnesia, might be for the police to video the process of taking evidence. There might be a case for caution to potential witnesses that they have a right to refuse to go on camera. But a video record of the statement and the demeanour of the person making it would make it much harder for anyone subsequently to change their mind, or claim they spoke under duress.
A great deal of work and effort has been put into upgrading witness protection, although there is probably scope for even greater improvements. However, a witness remains a free agent. He cannot be forced to take up the offer of protection. No matter how attractive the scheme, it is no substitute for being able to continue to live a normal life and spending the rest of his days on the run.
Nor can a corrupt witness be totally protected against the offer of bribes and inducements not to give evidence. However, it may be possible for police in sensitive cases to step up the amount of personal attention to individual witnesses in the months before a trial. Regular contact might help forewarn the prosecution that a witness is coming under pressure and could forestall a successful attempt at blackmail or bribery.
There will never be a wholly foolproof way to prevent witnesses turning hostile. Nor, for as long as presumption of innocence remains the basic principle of the common law will it always be possible to prosecute successfully without witness evidence.
However, there is always room for some improvement in witness management, which could limit the number of cases in which a prosecution has to be aborted at the last minute.