Montgomery v Lanarkshire Health Board
[2015] UKSC 11·2015·Appeal decision
A diabetic mother of small stature was not told of the roughly 10 per cent risk of shoulder dystocia in a vaginal birth or offered a caesarean, and her son was born with cerebral palsy. The Supreme Court held doctors must tell patients about material risks and reasonable alternatives, replacing the old doctor-knows-best approach to consent.
Since Montgomery, a claim can succeed where a patient was not warned of a risk that a reasonable person in their position would consider significant, even if some doctors would not have mentioned it. It underpins most modern consent-based negligence claims.