The Court of Appeal dimissed the appeals of Henry Momodou and Beher Limani against their convictions of violent disorder.
Their convictions had arisen out of a well-publicised, major and notorious disturbance at the Yarl's Wood Immigration Detention Centre in February 2002, some three months after the centre was opened.
On the appeal, an issue arose as to the effect on the safety of the conviction of the training techniques received by some of the witnesses.
Joel Bennathan (Registrar of Criminal Appeals) for the first defendant; Jollyon Robertson and Scott Ivill (Registrar of Criminal Appeals) for the second defendant; Nigel Rumfitt QC and Susannah Johnson (Crown Prosecution Service) for the Crown.
Lord Justice Judge said that there was a dramatic distinction between witness training or coaching, and witness familiarisation. Training or coaching for witnesses in criminal proceedings (whether for prosecution or defence) was not permitted.
The rule reduced any possibility that one witness might tailor his evidence in the light of what anyone else said, and equally, avoided any unfounded perception that he might have done so.
If arrangements were made for witness familiarisation by outside agencies, not, for example, that routinely performed by or through the Witness Service, the following broad guidance should be followed.
In relation to prosecution witnesses, the Crown Prosecution Service should be informed in advance of any proposal for familiarisation, and invited to comment in advance on the proposals.
The proposals for the intended familiarisation programme should be reduced into writing, rather than left to informal conversations.
If the defence engaged in the process, it would be extremely wise for counsel's advice to be sought, again in advance, and again with written information about the nature and extent of the training. In any event, it was a matter of professional duty on counsel and solicitors to ensure that the trial judge was informed of any familiarisation process organised by the defence using outside agencies, and it would follow that the Crown Prosecution Service would be made aware of what has happened.
The familiarisation process should normally be supervised or conducted by a solicitor or barrister, or someone who is responsible to a solicitor or barrister with experience of the criminal justice process, and preferably by an organisation accredited for the purpose by the Bar Council and Law Society. None of those involved should have any personal knowledge of the matters in issue.
Records should be maintained of all those present and the identity of those responsible for the familiarisation process, whenever it took place. The programme should be retained, together with all the written material used during the familiarisation sessions. None of the material should bear any similarity whatever to the issues in the criminal proceedings to be attended by the witnesses, and nothing in it should play on or trigger the witness's recollection of events.
If discussion of the instant criminal proceedings began, it had to be stopped, and advice given about precisely why it was impermissible, with a warning against the danger of evidence contamination and the risk that the course of justice may be perverted. Note should be made if and when any such warning was given.
All documents used in the process should be retained. It should be a matter of professional obligation for barristers and solicitors involved in such processes, or indeed the trial itself, to see that the above guidance was followed.