To lose a major criminal case on behalf of the prosecution is always a bitter experience. It is one which the writer has had many times, in both the ordinary courts and in the Special Criminal Court. Such an occurrence is inevitable. The standard of proof is beyond reasonable doubt. The Special Criminal Court is, like all continental European courts, staffed by judges.

Judges will try, when sitting as judges of fact in a criminal case, to apply the standard and burden of proof in the same way that they have seen juries apply it on countless occasions. A case can look un-loseable on paper. When you are inside a courtroom you can get a shock when the testimony you thought was unshakeable falls to pieces. Sometimes it doesn't even need cross-examination. The experience of a case improving for the prosecution when it looks weak on paper is rare.

No case can succeed if there are no witnesses. A person can, of course, convict himself. For many centuries the judiciary has kept a tight rein on the circumstances which will be allowed to condemn an accused on his own utterance. The majority of acquittals in confession cases are due to judges ruling a confession inadmissible in evidence on one or more legal grounds. More recently, the mood has been one of detached scrutiny as to every aspect of confession statements.

The defence has the complete prosecution papers (apart from the rare instance of undisclosed material) together with the custody record and the original notes of inter viewing gardai. Recent experience confirms that confession material is subject to scrutiny before it will move any body of judges or jurors to convict. Without a witness and with only a confession the prosecution faces an almost impossible burden.

Once the book of evidence is served on an accused the people who can link him to the crime are identified. They can also be intimidated. We have moved into the era of gangland crime where the commission of even murder is regarded as an appropriate price to pay to secure an acquittal. These dangers cannot be understated. Witnesses can be protected from them, but witness protection is the most invasive and burdensome destruction of a citizen's right to common privacy. Protection can be offered but can also be refused. Nothing less than the intense intrusion described offers protection. Extra Garda attention to a house or a person leaves huge windows of opportunity for intimidation. Yet this inadequate system is all most of us could stand. There is a scheme for witness protection. How it is applied may need to be revised. Even still it will not work unless the witness accepts it.

Murder happens when one person kills another and means it to happen. Manslaughter happens when a person's death is brought about in an assault or by criminal negligence. The courts have been scrupulous not to follow older English case law which artificially imposes a murder conviction simply because a person was part of a gang.

Carrying lethal weapons raises an inference that they are intended to be used as such if necessary: a gun can also be used to intimidate. Who is to say what the plan of action be fore a robbery is? Unless the prosecution can prove an intent to use lethal weapons with lethal effect against all the members of a criminal enterprise, the prosecution will fail.

If a defence is mounted that, contrary to an agreed plan of carrying weapons for intimidation, one member of a gang unexpectedly shoots somebody, then if there is a reasonable doubt the people who do not shoot are entitled to an acquittal.

All deserve, provided the evidence is there, to be convicted of robbery: all deserve, provided it can be proven against them, to be convicted of manslaughter, either through joining in an assault (which can be an aspect of intimidation with firearms) or through their criminal negligence in risking other people's lives by going about armed with lethal weapons for their own criminal profit.

It is all very well to say that death in a robbery is murder. It is. The awesome burden the prosecution bears is proving it against a background of legal rules which rightly seek to scrutinise, even against the most obvious facts, the state of mind of every individual accused and to allow each the benefit of the beyond-reasonable-doubt standard. The fact that something has happened and the fact that something can be proved are a chasm apart.

The Supreme Court has characterised the function of prosecution counsel by describing them as ministers of justice. There is a fiercely guarded tradition in Ireland of pursuing the attainment of justice by those who appear on behalf of the DPP. That office, set up in 1974, has a proud record of abiding in spirit and in fact by the independence that legally characterises the discharge of its function.

More than any other body of people in the State, they have faced the disappointments of being unable to bring home a serious criminal charge when the public interest would appear to demand it. More than any other body of people they understand, through experience, how what should be achieved may not be achieved. A prosecution cannot succeed without strong evidence.

Where the evidence is lost in the course of a case the overriding aim of pursuing justice remains. This is why, for example, a case of rape may be characterised as sexual assault, because the accused has offered a plea to that offence. It will remain and has to be treated for all practical and legal purposes as the official record of that event.

It may not be complete justice, but if justice is sought, then to go at least some way towards attaining it may be better than no justice at all. Often, such pleas are offered and accepted, not because of the penitence of the accused but because of the perceived weaknesses in the prosecution case.

The victim is an alcoholic; the gardai have arrested on the wrong charge; there is insufficient evidence to ground a reasonable suspicion in the application for a search warrant. The list can be endless of what can stop the truth asserting itself.

These things are known usually from the court papers. It can happen, and does happen more than rarely, that something that needs to go right for a case goes badly wrong after it has started. Surely in those cases the imperative of pursuing justice requires that a pragmatic response is right. There is no point in any other course. At least we have approached doing justice. What can be worse for a case than to lose its central witness? When that happens there must be a rethink.

In this country the rule is that the prosecution is not allowed to approach the defence to ask for a plea of guilty to any particular charge. If the defence offer a plea to a lesser charge then the burden of decision falls upon the DPP. It is a matter of assessing the case, taking into account the views of those who have been wronged, but ultimately it has to be faced that a disappointing reality is better than a catastrophic result.

The Good Friday agreement follows the theory of those expert in conflict resolution, that essential to the process is the release into the community of those who have perpetrated the appalling wrongs on behalf of each side. We have seen one case already where the High Court has characterised the agreement as a political document.

The only possible way it can give rise to legal rights is by creating a legitimate expectation on the part of those it addresses that they may be released early. If those general words are accompanied by a specific exclusion in relation to one particular crime, then the courts may well feel compelled to follow that line of common law authority which states that any impression created by a document will not give rise to legal rights if it is dispelled by disavowal or exclusion.

Peter Charleton is a practising barrister and the author of books and articles on criminal law and other topics, published in Ireland and in international journals