Derbyshire County Council v A Mother and A Father

In care proceedings involving allegations of salt poisoning, the court must determine the factual issue on the balance of probabilities. Expert medical evidence must be assessed within the whole evidential and factual context, including credibility and the circumstances in which the medical findings arose.

Expert guidelines assist the court but are not mandatory requirements. A diagnosis may properly be made despite missing recommended data where the expert evidence, clinical presentation, biochemical findings and recovery pattern provide a sufficiently reliable basis for the conclusion. Experts assist; the judge determines the facts.

These were care proceedings concerning children A and O. A had significant medical history, including a gastrostomy, while O had quadriplegia, secondary cerebral palsy and visual impairment. Concerns had arisen about the mother’s misrepresentation of A’s medical condition, which she substantially accepted.

The local authority sought findings that the mother had caused two episodes of acute hypernatraemia suffered by A while he was in hospital in July 2012 by administering salt through his gastrostomy tube. The mother was not called to give evidence. The court was invited to determine that issue solely on the medical evidence, against the background of the mother’s admitted conduct.

1. Applicable standard. The local authority bore the burden of proof. The standard was the simple balance of probabilities, neither more nor less, as stated in Re B UKHL 35. Inherent probabilities were relevant only as part of deciding where the truth lay.
2. Assessment of expert evidence. Medical evidence had to be analysed carefully, fitted into the factual matrix and tested against the witnesses’ credibility and the broader circumstances, in accordance with the approach identified in W v Oldham MBC [2006] 1 FLR 543 and Webster v Norfolk County Council [2009 EWCA (Civ) 59. The court also applied the principle in Re B (Care: Expert Witnesses) [1996] 1 FLR 667 that experts advise but the judge decides on the evidence.
3. Medical analysis. The possible causes of hypernatraemia were kidney malfunction, salt overload and dehydration. A’s kidney function was normal. The absence of clinical dehydration, normal renal and bicarbonate findings, raised chloride, substantial urine output and rapid correction of the sodium levels all pointed towards salt overload rather than dehydration. The two episodes had to be considered separately and also against the wider context.
4. Guidelines. The expert guidelines on differentiating salt poisoning from other causes were helpful but not mandatory. The absence of urine chemistry and weight measurements did not prevent a diagnosis where the remaining evidence, interpreted by an expert with appropriate specialist expertise, justified it.
5. Disposition. The judge accepted Dr Coulthard’s evidence and found, on the balance of probabilities, that the mother administered salt to A through his gastrostomy tube on both occasions.