Romani and Traveller communities experience long-standing structural inequalities, discrimination, and exclusion from health and social care services. For adults living with cognitive impairments, mental health difficulties, or neurological conditions, these inequalities can heighten anxieties about statutory intervention, particularly fears of arbitrary detention in hospitals or care homes. Despite the significance of these concerns, little is known about how professionals determine whether the detention of Romani and Traveller adults genuinely reflects their best interests. This study examines how best interests assessors (BIAs) respond to the needs of Romani and Traveller adults subject to the Deprivation of Liberty Safeguards in England and Wales. Drawing on Habermas’s system–lifeworld framework, two group interviews were conducted with thirty-five BIAs and allied professionals across four local authorities in North West England. The findings illustrate how structural inequalities and institutional practices marginalize cultural perspectives, contributing to the colonization of the lifeworld and undermining rights-based approaches to assessment. By placing these issues at the centre of analysis, the study contributes to growing calls for statutory systems that not only safeguard individuals but also actively promote dignity, autonomy, and social justice within the cultural contexts in which decisions about care and liberty are made.