The law binding disclosure must be made clearer

In 2006 Stuart Gair's 1989 murder conviction was quashed by the Appeal Court because his defence lawyers weren't provided with statements given to police by an important witness in the case against him. They showed the witness was prepared to tell lies, given to fantasising and willing to change his account when it suited him. The defence were also not told he had been in a mental hospital.

In George McPhee's appeal in 2005, it became apparent a report existed at the time of his 1987 trial in which scientists attempted to establish the size of footprints made at the crime scene. At the trial the footprints were of critical significance. Police officers' evidence went unchallenged as to the size of the shoe that made the prints. This evidence tended to implicate the accused and exculpate the incriminee. The scientists had considered it impossible to determine the shoe size. The fact their findings were not disclosed led to the conviction for murder being quashed.

In 1998, in the case of McLeod, the Appeal Court in Scotland said the Crown have "a duty at any time to disclose to the defence information in their possession which would tend to exculpate the accused" and "all material evidence for or against the accused".

Now Lord Coulsfield in his Review of Disclosure has said: "The duty of the prosecutor is to disclose to the defence all material evidence or information which would tend to exculpate the accused whether by weakening the Crown case or providing a defence to it."

It took the Crown until 2005 to implement a system which disclosed police statements of witnesses to the defence and previous convictions and pending cases of certain but not all witnesses. This new system by the Crown was prompted by decisions of the Judicial Committee of the Privy Council in the appeal cases of James Holland and Alvin Sinclair. The Judicial Committee held in both cases non-disclosure by the Crown of relevant material contravened Article 6(1) of the European Convention on Human Rights (ECHR) which guarantees the right to a fair trial.

Against this background, a Review of Disclosure became necessary. The task given to Coulsfield was complex - at the heart of disclosure lies a profound conflict between the interests of the defence, which desires all material assisting a client, and public interest in ensuring sensitive or confidential information is kept out of the public domain. Coulsfield proposes legislation to clarify the legal requirements of disclosure and to establish a mechanism for resolving conflicts of interest arising when disclosure of important material might put witnesses or security interests at risk. He addressed circumstances in which material may be withheld from the defence where disclosure would be prejudicial to individuals or the public interest in preserving security and preventing or detecting crime. He recommends Public Interest Immunity hearings similar to England and Wales, which take three forms:

• Prosecutor informs defence of category of the material at issue. Defence allowed to make representations at an inter-parties hearing.

• Prosecutor tells defence an application is being made but gives no details of category of material. Defence may make broad statements to court but hearing then proceeds in absence of defence and accused.

• Defence not notified and hearing takes place entirely in their absence.

The second and third of these are problematic as they deny the defence a chance to make representations with respect to the material, and these types of hearings arguably breach Article 6 of ECHR. According to Coulsfield, disclosure is to be limited to relevant and material information. Prosecuting authorities have to decide whether evidence has exculpatory value. This is problematic because prosecutors may not fully appreciate the significance of evidence to the presentation and preparation of an accused's defence.

Coulsfield says police should tell the Crown everything they know apart from the manifestly irrelevant. This proposal is sound in principle but will it work in practice?

I hope the Scottish Government shows it is serious about disclosure by ensuring police and the Crown have resources to meet the challenge it brings. It is so important for future legislation regarding disclosure to be right.

• Niall Mccluskey is an advocate specialising in criminal law.