Prior to December 1981, the prosecution's main duty was to disclose to the defence the names and addresses of witnesses who were not being called by the prosecution, but from whom statements had been taken (R v Bryant and Dickson (1946) 31 Cr App R 146).In later cases, this was interpreted to include two further instances.

Where a witness, whom the prosecution calls or tenders, gives evidence in the box on a material issue, and the prosecution have in their possession an earlier statement from that witness substantially conflicting such evidence, the prosecution should, at any rate, inform the defence of that fact (R v Howes 27 March 1950, unreported).

And, where the discrepancy involves detail, as in identification by description, it may be difficult to give such information to the defence without handing to them a copy of the earlier statement (R v Clark (1931) 22 Cr App R and R v Baksh [1958] AC 167).

There were also cases where the court had ordered the defence to be handed statements made to the police by witnesses for the prosecution.In addition, Lord Denning MR in Dallison v Caffery [1964] 2 All ER 610 said: 'The duty of a prosecuting counsel or solicitor, as I have always understood it, is this: if he knows of a credible witness who can speak to material facts which tend to show the prisoner to be innocent, he must either call that witness himself or make his statement available to the defence.'This case is authority only for the prosecution to supply the names and addresses of the witnesses, and not to supply a copy of the statements.

Most prosecuting authorities accept that the better practice is to supply a copy of the statement of the witness.

The practice in the 1960s and 1970s was for the Crown to supply on a 'counsel to counsel' basis, prior to a trial on indictment, copies of the statements.

They were often never shown to defence solicitors, but at the last minute the defence solicitor would find him or herself chasing around to look for witnesses and to take proofs.Prior to 1981 there was also a common law duty to disclose previous convictions of prosecution witnesses.

This was emphasised in the case of R v Knightsbridge Crown Court, ex p.

Goonatilleke [1985] 2 All ER 498, where the conviction of the applicant for shoplifting was quashed after it was discovered that the only prosecution witness to fact, the store detective, had a previous conviction for wasting police time, which had not been disclosed to the defence.

The store detective had been a police officer, but had left because of the conviction.The common law position was fortified by the issue of the Attorney-General's guidelines (see (1981) 74 Cr App R 302) which are advisory only and do not have any statutory authority.The duty of the prosecution as summarised in R v Judith Ward [1993] 2 All ER 577, is: 'Where the prosecution have taken a statement from a person whom they know can give material evidence, but decide not to call t he person as a witness, they are under a duty to make that person available as a witness for the defence.' 'Material evidence' means evidence which tends either to weaken a prosecution case, or to strengthen the defence case.Unless there are good reasons for not doing so, the duty should normally be performed by supplying copies of the witness statements to the defence, or by allowing them to inspect the statements and make copies.

If there are good reasons for not supplying copies, the duty can be performed by supplying the name and address of the witness to the defence.In relation to statements recording relevant interviews with the accused, subject to the possibility of public interest immunity (PII), the defence is entitled to be supplied with copies of all such statements.The Crown Court (Advance Notice of Expert Evidence) Rules 1987 provide that the prosecution must disclose any observation or tests which tend to disprove or cast doubt upon the opinion expressed in used material.

The process can often be simplified by the prosecution expert supplying his or her results and any necessary working papers to the expert advising the other party directly.Where the prosecution wishes to rely on PII or sensitivity to justify non-disclosure then, whenever possible P which would be in most cases P the prosecution must: give notice to the defence that they are applying for a ruling by the court; indicate to the defence at least the category of the material held; and give the defence the opportunity of making representations to the court (R v Davis [1993] 2 All ER 643).Normally the application will be made inter partes, but occasionally the Crown may have to make an application ex parte.

These would be in highly exceptional and rare cases.Where the prosecution is unable or unwilling to make an application to the court or neglects to do so, the defence should consider issuing a witness summons duces tecum to compel the witness to produce the documents.At the hearing to decide whether material which the prosecution claims is subject to PII should be disclosed, the judge must read the documents, which are the subject of the application.

If PII applies, then the judge must carry out a 'balancing exercise' to determine whether the interest of the party claiming PII outweighs the interest of the defence in insisting on disclosure (see R v Governor of Brixton, Prison ex p.

Osman (1) [1992] 1 All ER 108 and R v Clowes [1992] 3 All ER 440).Although the guidelines contemplated the disclosure only of documents, developments in the last 12 years show that unused material can also include photographs, audio tapes, video tapes, computer stored material, film negatives, televised material, and forensic evidence.It is clear that a defence solicitor would be failing in his or her duty if a request for disclosure of unused material was not made to the prosecution, even in a fairly simple case of a guilty plea, unless it is obvious that there is no such material, eg in a shoplifting or road traffic case.

There might be information which would result in advice being given to a defendant about the proper plea or which might help in mitigation.As regards the inspection of unused material, in cases where there are under 125 pages and the prosecution is going to supply photocopies, there is no serious problem.

It should, however, be read with care and should be included with papers delivered to counsel.In cases where the material is extensive or bulky P in a recent SFO prosecution, there were about 840 boxes of unused material in unheat ed vaults under the Northern Line P the prosecution should provide a list of the material.

If the prosecution wishes the defence to inspect the material before supplying copies, several problems have to be considered.-- When should the material be inspected? There is often little point in inspecting material, eg in a case of alleged fraud, until one has had an opportunity not only to see the prosecution depositions and exhibits, but also to take instructions on those papers so that one knows what to look for among unused material.

To look at unused material before fairly full instructions have been taken may result in a second inspection being necessary.

There are, however, occasions when, having inspected the unused material and asked for copies of particular documents, it may be necessary to trawl through it again.

For example, in a recent case, after the unused material had been inspected and discussed with the defendant, consideration was given during the trial to calling as a defence witness a person who was alleged by the Crown to be a co-conspirator although he had not been charged.

It was essential to inspect the unused material again to see what references there were to this alleged co-conspirator.

This could not be done until it was certain that he was not going to be charged as a defendant, and that there was evidence which he could give which might help the defence.-- Should the defendant inspect the material with the solicitors? Obviously there are problems if the defendant is in custody.

If the defendant is on bail, it is sometimes useful to take the defendant to inspect.

The question of whether or not to take the defendant might depend on the whereabouts of the unused material and of the defendant.Unused material is not always in a police station.

It may be inspected in the prosecuting solicitors' offices, including the Serious Fraud Office; liquidators' and receivers' offices; social services offices P in particular cases involving children; accountants' offices; and also in locations abroad.

For example, in Clowes, receivers in Gibraltar had possession of a large quantity of material which needed to be inspected and which was disclosed pursuant to the A-G's guidelines.

Visits to Gibraltar for this purpose were claimed and paid for as part of the legal aid costs.Until the last year or so, prosecuting authorities have not charged for provision of copies of material.

It is essential, however, that in cases where the Crown is not prepared to provide copies of all the material, the solicitors should not ask for all the material without first inspecting it and making a considered decision about each document which is to be copied.Since it is the duty of the prosecution to disclose material, and since it is the duty of the defence to inspect it and to use the material for the preparation of the defence, it is the view of the Law Society that the prosecutor must provide such copies as the defence requires, free of charge.

Recent notices from prosecuting authorities asking for payment of 14p per copy should be challenged on the basis that there is no statutory power to charge.

The Law Society believes the position may be analogous with the need for local authorities to have powers to charge.

This was considered by the House of Lords in McCarthy and Stone (Develop-ments) Ltd v Richmond upon Thames LBC [1991] 4 All ER 897.

The principle was well established in connection with the Crown in A-G v Wilts United Dairies Ltd (1922) 91 LJKB 897.The CPS has this month suspended its practice of seeking payment for unuse d material.

It is anticipated that other prosecuting authorities will follow suit.

In many cases, the prosecution evidence is on computer disk: unused material can include the original disks.

The Legal Aid Board has authorised the cost of any software needed in order to access the material, but will not pay for hardware as this is a capital expenditure.

For example, in the Maxwell case, it will almost certainly be necessary for the defence lawyers to invest in an optical disk reader where the capital expenditure may be in excess of £10,000.

The LAB has made it clear that although this might only be used for one case, it is not prepared to sanction the expenditure on a prior authority application.In rare cases, such as Ward, unused material can come to light after conviction and/or sentence and even, of course, after appeal procedures have been completed.If this does happen, it is vital for the defence solicitor to ascertain the nature of the material and to take instructions from the client on whether to inspect it.

If there is any doubt, the material should always be inspected.

If it is material, consideration must be given to the question of an appeal or, if appropriate, re-opening an appeal.Unless one is privately instructed, the green form may apply.

If it does not, the solicitor may have to bear the cost him or herself.