Well, apparently, no one!
The Countess of Mar tabled a written question that asked the Government: “What person or organisation is legally liable for the wellbeing of benefits claimants who are found to be fit for work under the work capability assessment and who are then made to work?”
In his written reply on 19 December 2012, the Minister for Welfare Reform at the Department for Work and Pensions (Lord Freud) replied:
The purpose of the work capability assessment (WCA) is to assist DWP decision-makers in assessing eligibility for benefit, or levels of benefit. The WCA is not a medical diagnosis and the decision affects benefit only; it does not oblige anyone to work.
Whilst the Secretary of State for Work and Pensions is legally responsible for all benefit decisions made by officials of the department on his behalf, there is no legal responsibility held by the Secretary of State for the well-being of benefit claimants.
Therefore, neither DWP nor WCA healthcare professionals are liable for any adverse consequence suffered by a claimant following a decision that the claimant is fit for work or for work-related activity.