Disclosing all relevant evidence to the defence is a fundamental part of criminal trials, writes Carol Coulter, Legal Affairs Correspondent
In a criminal trial, lawyers for the accused are not meant to be taken by surprise. They should know what the case against their client is so they can meet it, according to an expert in criminal law. This includes anything that might weaken the prosecution case and help the defence.
When a prosecution is prepared, the statements made by witnesses, with relevant documentation, are collected into a book of evidence, which is made available to the defence team. They then prepare the case knowing what the case against their client is and what the client says in response to it.
The Irish law on disclosure is not totally clear. The courts have ruled in the past that all "relevant" material must be disclosed to the defence. However, it is not clear who decides what is relevant.
For example, in the recent McKevitt case in the Special Criminal Court, there was lengthy legal argument about the admission of details of contacts between an informer and the Garda and RUC which, according to the prosecution, was privileged and not directly relevant to the trial. The defence argued that the decision on relevance should not be a matter for the prosecution.
The issue of privilege in relation to certain types of evidence - it is usually claimed when matters of state security or the possible safety of informers is invoked - may be clarified by the European Court of Human Rights.
However, the question of privilege did not arise in this case, where two members of the Garda gave evidence that was not outlined in their statements as contained in the book of evidence. This was evidence of their opinion concerning the circumstances of the death of the victim. The solicitor for the accused said that if the defence had been aware of it, they would have sought their own expert evidence on the same facts.
So Mr Justice O'Higgins ordered a new trial.