"Poison Parents" or "victims of circumstantial evidence"?

I see from http://www.emedicine.com/med/topic543.htm that the frequency of "Diabetes Insipidus" is - in the US, at least - about 1 in 25,000. Of these some 30% are idiopathic, in other words of no known cause.

So the appeal of Ian and Angela Gay against their conviction for poisoning a child by force-feeding him with at least four and a half teaspoons of salt on the grounds that according to a professor of neuro-endocrinology diabetes insipidus is a more likely cause has to be at least plausible:

Albeit improbable, it's still more likely than the even more outlandish diagnosis of salt poisoning.

And with Tony Blair trying to reduce the burden of proof these things are likely to happen more often than in the past.