Suspected non-accidental injury cases require precise, multi-disciplinary medical expert evidence. This guide explains the expert disciplines involved, how courts approach the medical evidence, and how to instruct the right expert for NAI proceedings.
Non-accidental injury (NAI) is the term used in family court proceedings to describe physical harm to a child that is not consistent with an accidental explanation. The term encompasses a spectrum of injuries — fractures, subdural haematomas, retinal haemorrhages, bruising, burns, and internal injuries — where the mechanism of injury, the developmental stage of the child, or the pattern of presentation raises concern that the injury was deliberately inflicted or caused by neglect.
The threshold for significant harm under section 31 of the Children Act 1989 is frequently engaged in NAI cases. The local authority must establish, on the balance of probabilities, that the child has suffered significant harm attributable to the care given by the parent or carer. Medical expert evidence is central to that determination — and to the identification of the perpetrator where the pool of possible perpetrators is limited.
The House of Lords' decision in Re H and R (Child Sexual Abuse: Standard of Proof) [1996] AC 563 and the Supreme Court's later clarification in Re S-B (Children) [2009] UKSC 17 confirm that the standard of proof in care proceedings is the civil standard — the balance of probabilities — applied without any enhanced threshold for serious allegations. The seriousness of the allegation may affect the cogency of evidence required, but it does not raise the standard itself.
No single expert can address all the medical questions that arise in a complex NAI case. Courts routinely hear from multiple specialists, each addressing a specific aspect of the injury presentation.
The lead expert in most NAI cases. Paediatricians assess the overall presentation, review the clinical history, and provide an opinion on whether the injuries are consistent with the explanation given. They also address the child's developmental stage — a factor critical in assessing whether an injury is plausible given the child's age and mobility.
Instructed to interpret skeletal surveys, MRI scans, and CT imaging. Radiologists can date fractures, identify healing patterns, and assess whether the imaging findings are consistent with the proposed mechanism of injury. The dating of fractures is a specialist skill that requires careful analysis of periosteal reaction, callus formation, and cortical bridging.
Essential in cases involving suspected shaken baby syndrome (now more commonly referred to as abusive head trauma). Retinal haemorrhages — particularly those extending to the periphery and involving multiple layers — are strongly associated with inflicted head injury, though the precise mechanism remains a subject of ongoing scientific debate.
Instructed in cases involving subdural haematoma, diffuse axonal injury, or other intracranial pathology. These experts address the biomechanics of the injury, the timing of bleeding, and whether the findings are consistent with a short fall or a more forceful mechanism.
Where a bleeding disorder is raised as an alternative explanation for bruising or intracranial bleeding, a haematologist assesses whether the child's coagulation profile and platelet function are consistent with a medical cause. Conditions such as glutaric aciduria type 1 and vitamin D deficiency may also be relevant in fracture cases.
The Court of Appeal's guidance in Re U; Re B (Serious Injury: Standard of Proof) [2004] EWCA Civ 567 remains the leading authority on the approach courts should take when evaluating medical evidence in NAI cases. The court must consider all the evidence — medical and non-medical — in the round. A medical opinion that an injury is consistent with NAI does not, by itself, establish that NAI occurred.
Lady Hale's judgment in Re J (Care Proceedings: Possible Perpetrators) [2013] UKSC 9 addressed the identification of perpetrators in NAI cases. Where the court cannot identify a specific perpetrator, it may make a finding that the harm was caused by one or more members of a limited pool, provided there is a real possibility — not a mere speculation — that each member of the pool caused the harm.
Courts are increasingly alert to the limits of expert evidence in NAI cases. The judgment in Re R (Care Proceedings: Causation) [2011] EWHC 1715 (Fam) emphasised that courts must not simply defer to expert opinion. The judge must evaluate the expert evidence critically, consider alternative explanations, and make findings of fact based on the totality of the evidence.
The standard of proof is the balance of probabilities — there is no heightened standard for serious allegations.
Medical evidence must be considered alongside all other evidence, including the parents' accounts, their credibility, and the history of the family.
Courts must guard against the 'jigsaw' approach — treating each piece of evidence in isolation rather than in the round.
An expert who says an injury is 'consistent with' NAI is not saying it was caused by NAI. The court must make that finding.
Where experts disagree, the court must evaluate the reasoning, not simply prefer the majority view.
The identification of a perpetrator requires a real possibility, not mere suspicion.
The letter of instruction in an NAI case must be drafted with precision. It should identify the specific injuries, set out the history given by the parents, and ask the expert to address the mechanism, timing, and causation of each injury. Where there is a proposed alternative explanation — such as a medical condition, a short fall, or a birth injury — the expert must be asked to address that explanation directly.
In complex cases involving multiple injuries or multiple experts, a joint experts' meeting is often directed by the court. The purpose of the meeting is to identify the areas of agreement and disagreement, and to produce a schedule of agreed and disputed findings. This process narrows the issues for the final hearing and reduces the time spent on expert evidence at trial.
Timing and timetabling
NAI cases are subject to the 26-week timetable under section 32 of the Children Act 1989. Applications to instruct experts must be made early. A skeletal survey should be arranged within 24 hours of admission in acute cases. Delays in instructing experts can prejudice the timetable and, in some cases, the quality of the evidence — particularly where injuries are healing and imaging findings are time-sensitive.
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