Cassidy v Ministry of Health [1951] 2 KB 343

C entered a hospital for an operation on his left hand, which necessitated post-operational treatment. While undergoing that treatment he was under the case of the surgeon who performed the operation who was a whole time assistant medical officer of the hospital, the house surgeon and members of the nursing staff of the hospital, all of whom were employed under contracts of service. At the end of his treatment, it was found that his hand had been rendered useless. The action had originally been brought against the Liverpool Corporation as owning and controlling the hospital, but later by virtue of s.6 the National Health Service Act 1946, the Ministry of Health were substituted as defendants. The trail judge dismissed his action for damages for negligent treatment which he brough against the hospital on the grounds that he had failed to prove any negligence C appealed.

Did the treatment outcome support an inference of negligence requiring an explanation from the hospital, despite the patient’s inability to identify the particular staff member responsible?

The Court of Appeal allowed the patient's claim. The outcome of treatment provided a prima facie basis for inferring negligence which the hospital had not adequately explained. The patient did not have to identify precisely which member of the treatment team had caused the damage where those responsible were within the hospital's responsibility. The court also rejected an approach which insulated a hospital from responsibility simply because medical staff exercised professional skill. Cassidy is therefore important for both the evidential inference and hospital responsibility. It does not establish that every unsuccessful medical treatment proves negligence or that an adverse outcome reverses the legal burden in every clinical claim.

A hospital may be responsible for negligent treatment by its staff despite their professional independence. Where the circumstances support an inference of negligence, inability to identify the particular staff member at fault need not defeat the patient's claim; an adverse outcome alone is not enough.

Cassidy combines institutional responsibility with evidential reasoning in a setting where the patient could not observe the treatment. It is often associated with res ipsa loquitur, but that label should not replace analysis of why negligence can be inferred. Modern discussion should also distinguish vicarious liability for employees from a non-delegable duty concerning treatment entrusted to others. The case does not remove the need to establish breach and causation in clinical negligence.