The investigative role of the Police gives them very much a monopoly over the collection of information. Several lines of enquiry might have been followed and a considerable volume of information obtained though the prosecution may not need to use all of it in a particular case. In our adversarial system, the defence plays a reactive role. This raises the question of "disclosure" - should ALL of the information gathered by the Police be disclosed to the defence?
The common law did not cover itself with glory over the question of disclosure. It was not until 1946 that the Court of Criminal Appeal held in R v Bryant and Dickson (1946) 31 Cr App R 146 that where the prosecution took a statement from a person whom they knew could give material evidence but whom they did not call as a witness, they had to make that person available to the defence. "Making available" required the name and address to be given but did not actually extend to supplying a copy of the statement. This state of affairs lasted until the House of Lords decision in R v Mills and Poole  UKHL 35.
Numerous examples can be given of cases where non-disclosure led to injustice. Examples include:
- Walter Rowland - hanged for murder in 1947 - evidence supporting his alibi had not been disclosed.
- The 1969 theft case of Laszlo Virag - discussed in Lord Devlin's report.
- The 1969 Luton Post Office murder case - R v Cooper and McMahon (1965) 65 Cr App R 215 and (1978) 68 Cr App R 18.
- The notorious 1975-76 Birmingham Six case where one pillar of the Crown case was that Dr Skuse's Greiss test was specific for nitroglycerine. One of his colleagues - Dr. Bamford - had obtained positive results with the same test that same night from the hands of two salesmen on the Belfast ferry. This remained undisclosed at trial and even after the unsuccessful 1987 appeal.
- Examples could be multiplied - e.g. Guildford Four and Maguire Seven.
Guidelines relating to disclosure were issued by the Attorney General in 1981. These amounted to internal instructions to the Crown Prosecution Service (CPS) and to prosecution counsel but the Court of Appeal was prepared to quash some convictions due to breaches of the guidelines.
In 1993, the Royal Commission on Criminal Justice issued its report - HERE. The discussion on disclosure is at page 91 (Prosecution disclosure) and page 97 (Defence disclosure). The Commission noted that "it has long been accepted that Crown Court trials can only proceed on the basis of full disclosure by the prosecution of all the evidence in its possession that is relevant to the case." As even the brief history above shows, it is questionable whether full disclosure had been "long accepted" but, nevertheless, the Commission recommended that the general framework for disclosure be set down in primary legislation with detailed procedures to be governed by subordinate legislation or Codes of Practice as under PACE.
The outcome was the Criminal Procedure and Investigations Act 1996. It is instructive to look at the version as originally enacted as well as at the amended version. The Act was extensively amended by Part 5 of the Criminal Justice Act 2003 and see the Explanatory Notes. Attorney General Guidelines continue to exist - see CPS website - and these note that:
This week, the Criminal Justice Inspectorates, issued an important report "Making it Fair" which highlights concerns about disclosure.
Paragraph 1.3 of the report is devastating:
Various recommendations are made for improvement. The report concludes (para 11) by saying:
Here is a vitally important topic which could well be examined by the Justice Committee with a view to ensuring that disclosure operates effectively.
An investigation was conducted by Richard Horwell QC into the reasons for the collapse of a trial of Police Officers in 2011 - see Home Office July 2017 - Mouncher investigation report
That prosecution arose from the "Cardiff Three" case.
The report makes a number of important recommendations concerning disclosure - see para. 24.11 of the report - Mouncher Investigation Report