David Pittaway on liability and health screening negligence. David Pittaway is a barrister at No1 Serjeants' Inn and acted for the health authorities.

On 16 November 1999, the Court of Appeal (Lord Woolf MR, May and Hale LJJ) gave judgement in the cases of Penney Palmer and Cannon v East Kent Health Authority.

They are the only cases on liability to have reached trial after the inquiry conducted by Sir William Wells into the operation of the National Cervical Screening Programme at Kent and Canterbury (K&C) Hospital in the 1990s.

The appeal was dismissed but the general application of the Bolam test was affirmed.

The issues before the trial judge were threefold: what was seen on the individual slides, whether at the relevant time a screener exercising reasonable care could fail to see what was on the slide, and whether a reasonably competent screener, aware of what a screener exercising reasonable care would observe on the slide, could treat the slide as negative.

The trial judge's decision to accept the evidence of the claimants' experts, Professors Krauz and Cotton, that in each of the three cases a screener exercising reasonable skill and care could not have failed to see obvious abnormalities, was upheld.

The cases were all concerned with adenocarcinoma, which is the rarer of the two cervical cancers, the other being squamous. The Court of Appeal expressed the view that the cases turned very much on their own facts.

On 21 December 1999 at Sheffield County Court, the trial judge entered a judgment for the defendant in Taylor v Barnsley Health Authority, in a case of squamous cancer.

The claimant consented to judgment at the end of the evidence of her expert, Professor Cotton. Subsequent to the K&C trial research had been published that showed that false negative smears contained significantly fewer abnormal cells than true positive smears - of less than 200 abnormal cells. Each slide can contain between 100,000 and 200,000 cells. Cotton said that a single abnormal cell on a slide not seen by a screener was negligent.

For both claimants' and defendants' legal advisers, there is a difficult exercise in evaluating claims, in each case the claimant has tragically gone on to develop cancer. Taylor shows that in claims where there are a small number of abnormal, or possibly abnormal, cells, the defendant is able to succeed at trial.