Recent research demonstrates that despite increased attention and awareness by politicians and decision-makers, people with learning disabilities are still disadvantaged when engaging with the criminal justice system. It has been argued that shortcomings in providing support are because of criminal justice professionals lacking necessary skills and competencies in identifying and dealing with people who have learning disabilities. This study draws on qualitative data generated through unstructured interviews with custody sergeants from three different constabularies. It is argued that learning disability is constructed in relation to concepts of fairness and justice, which a custody sergeant may utilise in accordance with their perception of professional identity. These constructs influence custody sergeants in their decision about how individual detainees should be treated and what kind of support should be made accessible to them whilst being detained.