Mr Mason has sought and received permission to publish the full transcript of Seema Misra's trial.
Seema Misra used to be a Subpostmaster at West Byfleet Post Office in Surrey. Despite being convicted of the theft of £75,000 from the Post Office by unanimous verdict at Guildford Crown Court in Nov 2010 (and subsequently sent to prison whilst pregnant), Seema has always protested her innocence. Her case is currently being considered by the Criminal Cases Review Commission.
Since the BBC Inside Out South investigation in Feb 2011, alleged problems with the Horizon computer system and criticism over the way the Post Office suspended, sacked and prosecuted a number of its Subpostmasters has been the subject of a Select Committee Inquiry, two parliamentary debates (1 and 2), several more Inside Out investigations, two One Show pieces and a recent Panorama.
We know from the Panorama that the Post Office prosecuted one Subpostmaster for theft despite an internal investigator stating he could not find any evidence of theft. The Post Office says it cannot comment on individual cases due to confidentiality, but that a financial loss and false accounting together is often sufficient evidence for a theft charge. The Post Office maintains the Horizon system works fine and that it's never done anything wrong in any of the cases we've featured.
In his introduction to the Misra trial transcript, Mr Mason warns that the "the reader must take great care in reaching settled conclusions from the transcript of the trial, because the transcript is only one part of the entire record."
This does not stop Mr Mason from making considered, but repeated criticisms of the Post Office prosecution. Here he attacks a fundamental defence the Post Office have always made about the Horizon system - its "robust"-ness:
"To assert that a complex system, which the Horizon software appears to be, is ‘robust’, the prosecution ought to have produce [sic] evidence to establish what was meant by ‘robust’ and the truth of the claim.
"No evidence was produced to demonstrate that the system was ‘robust’, nor to establish the ‘quality’ of the system – none of the test [sic] set out in chapter 4 of Electronic Evidence seem to have been considered.
"The Post Office also failed to produce any evidence regarding the operation of the operating environment and the reconciliations, error rates, controls, and relevant internal audit processes used to ensure integrity, and to provide details of the various up- dates that fixed problems with the software."
He then goes on to address the issue of who actually controls the Horizon terminals in a Post Office:
"The comment that the defendant would have been aware of a defect in the software (excluding the specific defect discovered in a post office in Callendar Square in Falkirk) is manifestly incorrect.
"Neither observation was accurate, nor, it appears, sustained by any evidence produced at trial. Moreover, the observation (Day 1 Monday 11 October 2010, 23H – 24A) that Seema Misra was ‘the person responsible for the computer system at this office’ demonstrates the failure of the prosecutor to understand that end users of the Horizon system do not control the computer system: Fujitsu undertake this task."
Mr Mason then goes on to criticise the expert witness for the prosecution:
"Gareth Jenkins, the system architect for Fujitsu Services, was asked about the possibility that a problem that might arise between the systems [Horizon and Riposte], but he considered this was of no relevance, even though he did not know whether the problems encountered with the Riposte software might have affected the Horizon system (Day 4 Thursday 14 October 2010, 97 – 98).
"In effect, the prosecution did not present any witness for the defence to cross examine on this particular and important point, although it was admitted that the Escher software [Riposte] appeared to be the cause of the problem encountered at the post office in Callendar Square in Falkirk (examination in chief: Day 4, Thursday 14 October 2010, 46F – 50; cross examination: 88G – 111).
"Mr Jenkins relied on a great deal of hearsay in giving his evidence, he rarely obtained and submitted original data, and on occasions spoke to other people in Fujitsu Services to ascertain answers to technical questions – yet none of the people he spoke to were called to give evidence."
The assertion that it was only Seema Misra who was having problems with Horizon appears to have been contradicted during the trial:
"The previous owner of the post office run by Seema Misra claimed that they did not have any problems. It later transpired that this was not correct (Day 5, Friday 15 October 2010, 2 – 9).
"However, before the first owner of the post office made the additional admission, the prosecutor reached the false conclusion that because the first owner of the post office did not have any problems, it followed that there was no failure of the computer system at a later date (Day 1 Monday 11 October 2010, 50F)."
"Arguably, the evidence of the software system was not sufficient for anybody to make a decision based on the evidence put forward in the trial [my italics], and it seems that all Professor McLachlan [expert witness for the defence] could do was highlight the fact that he had so little evidence to consider, that he was not able to offer any sensible or conclusive conclusions."
In summary, a barrister who specialises in the presentation of electronic evidence in court believes evidence presented by the Post Office during a criminal trial was "arguably" not sufficient for a jury (or indeed "anybody") to reach an informed decision. In Seema's case the Post Office didn't offer any other evidence as to her guilt of theft, a point noted by the judge in his summing up to the jury.
A barrister's opinion is just that, a barrister's opinion. But the evidence required to convict someone of a criminal offence must be beyond reasonable doubt. Mr Mason believes the prosecution's evidence was arguably insufficient. The jury, without the benefit of Mr Mason's expertise, disagreed.
I've asked the Post Office to respond to Mr Mason's comments and will post up their reply if I get one.
Ongoing Computer Weekly investigation into Horizon and timeline
Post Office Horizon primer written by me in 2013