Since the King’s Fund publication ‘No decision about me, without me’, improving shared decision making has become a national priority (Coulter and Collins, 2011; Ross et al, 2018). One survey of 500 doctors found 82% admitted to prescribing treatments they consider unnecessary (Academy of Medical Royal Colleges, 2016), whilst over 30% of patients wish to have more involvement in decisions about their care (NHS England, 2018). The Montgomery ruling means there is now a legal imperative to discuss 'material risks' with patients. However, what really is ‘shared decision-making’ (or ‘SDM’ as it is commonly known)? Is it worth it? And don't we already do it?