When does a police officer qualify as an expert witness?

In R (Doughty) v Ely Magistrates’ Court, CPS (interested party) (CLW/08/20/2) the Divisional Court held that a court at first instance had acted unreasonably in deciding that a former police officer could not give evidence as an expert as to the workings of a speed detection device.

The magistrates’ court had reasoned that:

(i) the officer had retired from the police some years before and had therefore not had recent direct experience in using the device;

(ii) the officer had not attended courses on the device run by the manufacturer which had been attended by the expert prosecution witness and therefore did not have an equivalent level of expertise to that witness; and

(iii) the officer’s academic qualifications did not mean that he could assist the court on the workings of the device.

The Divisional Court held that this was the wrong approach since the matters the court had relied on were matters which went to the weight to be attached to the officer’s evidence and not to the question of whether he should be allowed to give evidence at all. It was further stated that it was of particular concern that the court had relied on his supposed lack of an equivalent level of expertise because this was the clearest of indications that it was relying on matters which went to comparative weight as a reason for ruling on the very admissibility of the evidence in the first place.

In addition, the Divisional Court said that:

(a) it was worrying that the court at first instance had relied on his lack of attendance at courses run by the manufacturer, since those courses were not open to defence expert witnesses;