The court of appeal in the successful appeals by Sally Clark and Angela Cannings has sent out strong messages about the difficulties of proper proof in cases involving the death of babies. Cot deaths are still little understood and at the frontiers of medical research.

The possibility of a "cot death gene" is being investigated and could provide an answer. But the reality, as pointed out in the appeal court, is that in a case where the allegation depends exclusively or almost exclusively upon expert evidence and experts of recognised distinction disagree, then it is likely to be unsafe to proceed.

The issues of who are experts and how they should be selected and have their evidence assessed are also pressing matters. The sustained attack on the evidence given in the past by Professor Sir Roy Meadow has focused attention on the role of the expert and the often overpoweringly persuasive effect it can have.

Should we also be thinking of preliminary screening and assessment of medical evidence before a trial begins? Should judges have medical assessors sitting with them to assist them or the jury in their decisions?

One of the most important messages from the court of appeal is that the Crown Prosecution Service must think long and hard before it begins prosecutions because of the likely evidential difficulties and the danger of miscarriages of justice.

Similarly the family courts must continue to approach allegations with great care when deciding whether to remove a baby from its parents. The tragedy of a child wrongly removed from its natural family is as great as that of a carer wrongly imprisoned for life.

The success of the Cannings and Clark appeals, and the acquittal of Trupti Patel, has led a number of commentators to question whether apparently loving mothers ever murder their babies, or that the condition formerly known as Munchausen syndrome by proxy (now generally called fabricated or induced illness), in which carers make up or cause illness in their children to attract attention to themselves, really exists.

However, numerous cases have been satisfactorily proved in the past in both the criminal and family courts based on credible confessions and cogent medical evidence.

A balanced view needs to be taken based on the primary guiding principle of protecting children from harm.

Although cases are notoriously difficult to prove to recognised court standards, one must remember that instances of covert video surveillance of carers by medical practitioners have demonstrated clear evidence of abuse, mainly attempted suffocation, in particular cases.

Everyone is looking to medical research to provide answers for the future in these difficult cases.

· Allan Levy QC is an expert in child law