R v Tunstill

The Court held that Section 1(1) of the Infanticide Act 1938 does not require the consequences of giving birth to be the sole cause of a disturbance of the mind, provided they are an operating and substantial cause.

The Appellant was convicted of the murder of her daughter. She had given birth to her in the bathroom of her home and then stabbed her 14 times, killing her. The Appellant was sentenced to life imprisonment, with a minimum term of 20 years.

Three experts, all consultant forensic psychiatrists, gave evidence to the court. All agreed that the Appellant was fit to plead. The defence experts gave evidence in support of both diminished responsibility and infanticide and the Crown expert gave evidence against both. The difficulty for the defence was the evidence seemed to be (in summary) that the Appellant had been mentally ill, to some degree, even prior to the birth.

Because it could not be said that the balance of the Appellant's mind was disturbed solely by reason of not having fully recovered from the effects of giving birth the trial judge held that there was no basis for an alternative verdict of infanticide, and removed the defence from the jury.
Held: The Court of Appeal found that this decision was incorrect. The court found that the phrase "by reason of" in section 1(1) does not need to be read as if it said "solely by reason of" and as long as a failure to recover from the effects of birth is an operative or substantial cause of the disturbance of the balance of mind that suffices, even if there are other underlying mental problems (perhaps falling short of diminished responsibility) which are part of the overall picture.

The conviction was quashed, and a re-trial ordered.