Summary: The Deprivation of Liberty Safeguards were introduced in England and Wales to protect the interests of people with learning disabilities, dementia and neurological conditions resident in hospitals and care homes. The Safeguards apply when residents lack capacity to make decisions about their care and treatment in circumstances that may amount to a deprivation of their liberty. Best Interests Assessors must establish whether a deprivation of liberty has occurred. However, there is no definition in statute; instead, the identification of factors which define a deprivation of liberty is evolving through case law. A factorial survey was used to identify the factors which influenced the professional judgements of 93 Best Interests Assessors (three-quarters social workers) who generated 798 responses to randomly generated vignettes.

Findings: Coercive staff behaviour was the strongest statistical predictor of a deprivation of liberty judgement, followed by the resident’s response. Other indicators of staff control, including the use of medication to reduce agitation, restriction of movement and family unhappiness with care were also significant. The resident’s condition, gender/age and the setting were not significant predictors. Best Interests Assessors were generally confident in their decision making; there were no differences in confidence associated with Best Interests Assessors’ professions.

Applications: Reviews of the operation of the Safeguards stress significant complexity in defining a deprivation of liberty. Nevertheless, this study suggests that the factors which Best Interests Assessors take into account are rooted in the fundamental principles of the Safeguards and an informed appreciation of case law. Best Interests Assessors and local authorities, in their role as supervisory bodies, must keep up to date with developments.