Post Office inquiry live: Ex-Fujitsu engineer Gareth Jenkins gives second day of evidence

We’ve heard a lot about what is expected of an “expert witness” in court, during today’s evidence.

Usually in court, people are called as witnesses because they saw something happen or might have some limited information important to a case.

An expert witness is called because they have a deep knowledge of their subject and, as such, they have some extra duties which go beyond the basics.

The CPS defines expert witnesses as having a duty to “help the court to achieve the overriding objective by giving opinion which is objective and unbiased”.

That duty is “owed to the court” – in other words, overrides any sort of loyalties to any side in a court case, even the one which puts them forward.

The CPS adds that expert witnesses are obliged “to disclose to the party instructing them anything (of which the expert is aware) that might reasonably be thought capable of undermining the expert’s opinion or detracting from their credibility or impartiality”.

Jenkins’ defence today is that he didn’t understand he was considered an expert witness, and therefore didn’t understand he would have been legally obligated to volunteer a full picture of Horizon’s faults.