Data (Use and Access) Bill [HL]

Debate between Lord Tarassenko and Earl of Erroll

Committee stage
Wednesday 18th December 2024 Grand Committee

[Lord Tarassenko (CB)]

My Lords, I will speak briefly in support of this amendment. Anyone who has written computer code, and I plead guilty, knows that large software systems are never bug-free. These bugs can arise because of software design errors, human errors in coding or unexpected software interactions for some input data. Every computer scientist or software engineer will readily acknowledge that computer systems have a latent propensity to function incorrectly.

As the noble Baroness, Lady Kidron, has already said, we all regularly experience the phenomenon of bug fixing when we download updates to software products in everyday use—for example, Office 365. These updates include not only new features but patches to fix bugs which have become apparent only in the current version of the software. The legal presumption of the proper functioning of “mechanical instruments” that courts in England and Wales have been applying to computers since 1999 has been shown by the Post Office Horizon IT inquiry to be deeply flawed. The more complex the program, the more likely the occurrences of incorrect functioning, even with modular design. The program at the heart of Fujitsu’s Horizon IT system had tens of millions of lines of code.

The unwillingness of the courts to accept that the Horizon IT system developed for the Post Office was unreliable and lacking in robustness—until the key judgment, which has already been mentioned, by Mr Justice Fraser in 2019—is one of the main reasons why more than 900 sub-postmasters were wrongly prosecuted. The error logs of any computer system make it possible to identify unexpected states in the computer software and hence erroneous system behaviour. Error logs for the Horizon IT system were disclosed only in response to a direction from the court in early 2019. At that point, the records from Fujitsu’s browser-based incident management system revealed 218,000 different error records for the Horizon system.

For 18 years prior to 2019, the Post Office did not disclose any error log data, documents which are routinely maintained and kept for any computer system of any size and complexity. Existing disclosure arrangements in legal proceedings do not work effectively for computer software, and this amendment concerning the electronic evidence produced by or derived from a computer system seeks to address this issue. The Post Office Horizon IT inquiry finished hearing evidence yesterday, having catalogued a human tragedy of unparalleled scale, one of the most widespread miscarriages of justice in the UK. Whether it is by means of this amendment or otherwise, wrongful prosecutions on the basis that computers always operate properly cannot continue any longer.

[The Earl of Erroll (CB)]

My Lords, if I may just interject, I have seen this happen not just in the Horizon scandal. Several years ago, the banks were saying that you could not possibly find out someone’s PIN and were therefore refusing to refund people who had had stuff stolen from them. It was not until the late Professor Ross Anderson, of the computer science department at Cambridge University, proved that they had been deliberately misidentifying to the courts which counter they should have been looking at, as to what was being read, and explained exactly how you could get the thing to default back to a different set of counters, that the banks eventually had to give way. But they went on lying to the courts for a long time. I am afraid that this is something that keeps happening again and again, and an amendment like this is essential for future justice for innocent people.