BackgroundThe UK government committed to legislating for Advance Choice Documents/Advance Statements (ACD/AS) following their recommendation by the Independent Review of the MHA (2018). ACDs/AS are yet to be implemented in routine practice despite evidence and high demand; they are associated with improved therapeutic relationships and a reduction (25%, RR 0.75, CI 0.61–0.93) in compulsory psychiatric admission. Barriers to their implementation are well documented, ranging from low knowledge levels to logistical challenges in accessing the content during episodes of acute care. In the UK this is an issue for Black people, who experience detention rates disproportionately (over three times) higher than those of White British people and have poorer care experiences and outcomes. ACDs/AS allow for Black people to have their concerns heard by mental health professionals in a care system where they often feel their views are ignored. AdStAC aims to improve Black service users’ experiences in mental health services in South London by co-producing and testing an ACD/AS implementation resource with Black service users, mental health professionals and carers/supporters of Black service users.Methods/designThe study will take place in South London, England over three phases: 1) formative work through stakeholder workshops; 2) co-production of resources through a consensus development exercise and working groups; and 3) testing of the resources using quality improvement (QI) methods. A lived experience advisory group, staff advisory group and project steering committee will support the study throughout. The implementation resources will comprise: advance choice document/advance statement (ACD/AS) documentation, stakeholder trainings, a manual for mental health professionals to facilitate the processes of creating and revising advance statements, and informatics development.DiscussionThe implementation resources will help increase the likelihood of the new mental health legislation in England being implemented effectively; through aligning evidence-based medicine, policy and law to effectively provide positive clinical, social and financial outcomes for Black people, the National Health Service (NHS) and wider society. This study will likely benefit a wider group of people with severe mental illness, as when marginalised groups who are least engaged, can be supported with these strategies, then the strategies are likely to work for others.