Questions remain over cause of head injuries in children

We have taken instruction in several ‘Shaken Baby’ cases, including appeals.  All of the cases have been resolved in favour of the client.  We are pleased that we are again using the published scientific literature to demonstrate deficiencies in the scientific evidence used in courts, even if that evidence has appeared to be accepted for a long time.  Concern about the availability of experts to challenge the diagnosis was raised several years ago.  An article and Editorial in New Scientist stated,

“Over the past decade, evidence has emerged to challenge the idea that the triad of symptoms constitutes unambiguous evidence of death through violent shaking….

A handful of convictions have been quashed on appeal, yet the dogma persists in the courts.

If anything, things are going backwards. In the UK, a pathologist who acts as an expert witness for people who protest their innocence in shaken-baby cases has been banned from giving evidence in court. This has made other doubters too frightened to give expert evidence lest they suffer the same fate.”[1]

In line with our belief in using the best science available to assess and if necessary challenge expert opinion, our purpose in these cases is to review the published literature to ascertain the scientific support for the proffered opinions on the diagnostic significance of the features used to support a diagnosis of Non-Accidental Head Injury (NAHI).  On that basis, we believe that there are serious problems in the way that this diagnosis is derived.

Non Accidental Head Injury

The diagnosis of Non-Accidental Injury (NAI) (the original term, Shaken Baby Syndrome (SBS) is now out of favour), has commonly been based on a combination of symptoms always including subdural haematoma (SH), retinal haemorrhage (RH), and sometimes including fractures, encephalopathy (disease of the brain affecting the brain's function) or even “a lack of explanation from the carer(s)”.

Even the replacement of the name “SBS” with “NAHI” is a dubious improvement on the aetiology of the death/injury in question, because both names still imply an assumption as to cause.  The diagnosis of “non-accidental injury” (NAI) therefore, is pejorative and should be better described as “unexplained injury”.

When the medical experts speak of ‘likely’ or ‘unlikely’ they must quantitate that for the court to be able to assess the weight of the evidence. It is this quantitation, and the bases of their assertions that the NAHI causation is more ‘likely’ than the alternative views, that offers the main scientific challenge to the evidence in such cases.

The medical and scientific literature which would enable medics to give a quantifiable opinion about the strength of competing hypotheses in alleged shaken baby cases is not complete. It is a complex and on-going area of controversy and debate, which does not mean that experts giving evidence in the meantime should be excused from having to substantiate their opinions with more than mere speculation, “experience” or information told to them by others and assumed to be true.  The difficulty is to clarify what expert evidence is based in probability (which is measured and measurable) and what is just personal opinion or a degree of belief based on something else.

We are concerned about the validity of a supposedly impartial process that provides others’ opinions to consultants prior to the consultant making their own observations and evaluation. There is a substantial body of research demonstrating the effect of this type of presentation; it falls within the remit of “reviewer bias” which can occur when the person collecting or reviewing data (either subjective or objective) is “aware of a suspected diagnosis or results of a reference test. This type of bias can also occur when reference test results are interpreted with knowledge of the study test results. For example, a pathologist might be more inclined to choose a certain diagnosis if the imaging appearance supports it. Reviews of the imaging literature have reported this to be a common bias.”[2]

The evaluation of evidence is fundamental to any scientific inquiry. It is especially important in the forensic arena where time may be limited and decisions must be made using whatever data is to hand. Without data the enquiry is essentially non-scientific. This does not necessarily imply that the opinions that are held are wrong, merely that there is no scientific way of assessing their worth. When applied scientists (such as medics) express opinions in terms of probabilities, no matter how imperfectly, they are clearly implying some scientific analysis has been possible.

The central issue in these cases is what evidential support the observations provide for an allegation of NAHI.

(For a comprehensive consideration of the legal history of this issue click this link)