Aims and method A group of lawyers, psychiatrists, best interest assessors and independent mental capacity advocates were asked to make binary judgements about whether real-life situations in 12 vignettes amounted to deprivation of liberty. Kappa coefficients were calculated to describe the level of agreement within each professional group and for the total group of professionals. Results There was total agreement between all professionals about deprivation of liberty in only 1 of the 12 cases. The overall level of agreement for judgements made by all professionals was ‘slight’ (κ=0.16, P<0.01). Clinical implications There are practical difficulties involved in making reliable deprivation of liberty judgements within the Deprivation of Liberty Safeguards (DoLS) legislation. A clear interpretation of deprivation of liberty is necessary to facilitate professionals’ decision-making in this area.