Data Protection and Digital Information Bill

Debate between Lord Arbuthnot of Edrom and Lord Clement-Jones

Committee stage
Wednesday 24th April 2024 Grand Committee

[Lord Arbuthnot of Edrom (Con)]

My Lords, I congratulate the noble Baroness, Lady Kidron, on her amendment and thank her for allowing me to add my name to it. I agree with what she said. I, too, had the benefit of a meeting with the Lord Chancellor, which was most helpful. I am grateful to Mr Paul Marshall—whom the noble Baroness mentioned and who has represented several sub-postmasters in the Horizon scandal—for his help and advice in this matter.

My first short point is that evidence derived from a computer is hearsay. There is good reason for treating hearsay evidence with caution. Computer scientists know—although the general public do not—that only the smallest and least complex computer programs can be tested exhaustively. I am told that the limit for that testing is probably around 100 lines of a well-designed and carefully written program. Horizon, which Mr Justice Fraser said was not in the least robust, consisted of a suite of programs involving millions of lines of code. It will inevitably have contained thousands of errors because all computer programs do. Most computer errors do not routinely cause malfunctions. If they did, they would be spotted at an early stage and the program would be changed—but potentially with consequential changes to the program that might not be intended or spotted.

We are all aware of how frequently we are invited to accept software updates from our mobile telephone’s software manufacturers. Those updates are not limited to security chinks but are also required because bugs—or, as we learned yesterday from Paula Vennells’s husband, anomalies and exceptions—are inevitable in computer programs. That is why Fujitsu had an office dedicated not just to altering the sub-postmasters’ balances, shocking as that is, but to altering and amending a program that was never going to be perfect because no computer program is.

The only conclusion that one can draw from all this is that computer programs are, as the noble Baroness said, inherently unreliable, such that having a presumption in law that they are reliable is unsustainable. In the case of the DPP v McKeown and Jones—in 1997, I think—Lord Hoffmann said:

“It is notorious that one needs no expertise in electronics to be able to know whether a computer is working properly”.


One must always hesitate before questioning the wisdom of a man as clever as Lord Hoffmann, but he was wrong. The notoriety now attaches to his comment.

The consequences of the repeal of Section 69 of the Police and Criminal Evidence Act 1984 have been that it reduces the burden of proof, so that Seema Misra was sent to prison in the circumstances set out by the noble Baroness. Further, this matter is urgent for two reasons; they slightly conflict with each other, but I will nevertheless set them out. The first is that for the presumption to remain in place for one minute longer means that there is a genuine risk that miscarriages of justice will continue to occur in other non-Post Office cases, from as early as tomorrow. The second is that any defence lawyer will, in any event, be treating the presumption as having been fatally undermined by the Horizon issues. The presumption will therefore be questioned in every court where it might otherwise apply. It needs consideration by Parliament.

My noble friend the Minister will say, and he will be right, that the Horizon case was a disgraceful failure of disclosure by the Post Office. But it was permitted by the presumption of the correctness of computer evidence, which I hope we have shown is unsustainable. Part of the solution to the problem may lie in changes to disclosure and discovery, but we cannot permit a presumption that we know to be unfounded to continue in law.

My noble friend may also go on to say that our amendment is flawed in that it will place impossible burdens on prosecutors, requiring them to get constant certificates of proper working from Microsoft, Google, WhatsApp, and whatever Twitter is called nowadays. Again, he may be right. We do not seek to bring prosecutions grinding to a halt, nor do we seek to question the underlying integrity of our email or communications systems, so we may need another way through this problem. Luckily, my noble friend is a very clever man, and I look forward to hearing what he proposes.

[Lord Clement-Jones (LD)]

My Lords, we have heard two extremely powerful speeches; I will follow in their wake but be very brief. For many years now, I campaigned on amending the Computer Misuse Act; the noble Lord, Lord Arbuthnot, did similarly. My motivation did not start with the Horizon scandal, but was more at large because of the underlying concerns about the nature of computer evidence.

I came rather late to this understanding about the presumption of the accuracy of computer evidence. It is somewhat horrifying, the more you look into the history of this, which has been so well set out by the noble Baroness, Lady Kidron. I remember advising MPs at the time about the Police and Criminal Evidence Act. I was not really aware of what the Law Commission had recommended in terms of getting rid of Section 69, or indeed what the Youth Justice and Criminal Evidence Act did in 1999, a year after I came into this House.

The noble Baroness has set out the history of it, and how badly wrong the Law Commission got this. She set out extremely well the impact and illustration of Mrs Misra’s case, the injustice that has resulted through the Horizon cases—indeed, not just through those cases, but through other areas—and the whole aspect of the reliability of computer evidence. Likewise, we must all pay tribute to the tireless campaigning of the noble Lord, Lord Arbuthnot. I thought it was really interesting how he described computer evidence as hearsay, because that essentially is what it is, and there is the whole issue of updates and bug fixing.

The one area that I am slightly uncertain about after listening to the debate and having read some of the background to this is precisely what impact Mr Justice Fraser’s judgment had. Some people seem to have taken it as simply saying that the computer evidence was unreliable, but that it was a one-off. It seems to me that it was much more sweeping than that and was really a rebuttal of the original view the Law Commission took on the reliability of computer evidence.