Bailey v Ministry of Defence [2009] 1 W.L.R. 1052 is an influential case for law students exploring clinical negligence, specifically focusing on causation in medical malpractice. This case helps clarify the threshold for establishing causation when direct evidence is insufficient to apply the “but for” test.

  • In the case of Bailey v Ministry of Defence [2009] 1 W.L.R. 1052, it was held that in clinical negligence cases, a patient can establish causation stemming from a lack of post-operative care where they demonstrate, on the balance of probabilities, this lack of care made a material (greater than negligible) contribution to the overall weakness of the patient’s condition, leaving them vulnerable to further damage.

Facts of the Case

  • On 9th January 2001, C was admitted to a hospital managed by D. On 11th January, an operation was carried out to remove C’s gallstone.
  • Following the procedure, C suffered symptoms of pancreatitis. Her treatment proved to be negligent before her transfer to another hospital.
  • As a result of the negligent treatment, C was left unable to clear vomit from her throat. Her choking caused a cardiac arrest, leading C to suffer brain damage.
  • C sued D, arguing that there was a lack of care in C’s resuscitation.
  • Proper care would have led to early intervention and prevented C from becoming as weak as she became.
  • C alleged that this weakness caused, or materially contributed, to her being unable to prevent herself from choking.


  • Could ‘material contribution to the damage’ satisfy the causation element of negligence and justify imposing liability on D?

Held by the Court of Appeal (Civil Division)

  • Finding for C, that D’s negligent treatment was a more than negligible cause of C’s brain injury and hence a material contribution.
  • In cases where medical science could not establish the probability that ‘but for’ D’s negligence C’s injury would not have occurred, this ‘but for’ test would extend to where D’s negligence materially contributed to the damage.

Waller L.J.

  • It is obvious that it was C’s weakened state which led to her being unable to respond naturally to her vomit. It is not alleged that her transfer to the renal ward, or the care she received there, broke any chain of causation of whatever caused her weakened state or whatever resulted from being in that weakened state. The question is what caused her weakened state.
  • If all that is necessary is a ‘material contribution’ and it is sufficient to establish that D’s contribution is more than negligible to prove material contribution, then D is liable. The question is whether that is sufficient. This would not be an application of the classic ‘but for’ test.
  • Lord Keith in Bonnington Castings v Wardlaw dealt with a case where the inadequacies of medical science meant that the claimant could not prove that but for the defendant’s negligence, the injury would not have occurred. Making this case more difficult is that there were multiple cumulative causes. He adopted the position that the claimant needed to prove a substantial (greater than de minimis) causative potency.
  • “In my view one cannot draw a distinction between medical negligence cases and others. I would summarise the position in relation to cumulative cause cases as follows. If the evidence demonstrates on a balance of probabilities that the injury would have occurred as a result of the non-tortious cause in any event, C will have failed to establish that the tortious cause contributed…If the evidence demonstrates that ‘but for’ the contribution of the tortious cause the injury would probably not have occurred, C will (obviously) have discharged the burden. In a case where medical science cannot establish the probability that ‘but for’ an act of negligence the injury would not have happened but can establish that the contribution of the negligent cause was more than negligible, the ‘but for’ test is modified, and C will succeed” [46]
  • This case involved cumulative causes acting so as to create C’s weakness and thus the judge applied the appropriate test that C only needed to prove that D’s negligence made a more than negligible contribution to the damage.

Significance of the Case on the Development of the Law

The Bailey v Ministry of Defence case significantly impacted the legal landscape regarding clinical negligence, particularly in how causation is established:

  1. Establishment of “Material Contribution” Test: This case was pivotal in reinforcing the “material contribution” test over the traditional “but for” test in scenarios where multiple potential causes exist for a patient’s harm. The court held that if a defendant’s negligence “materially contributes” to the harm, they can be held liable, even if the harm could have occurred without it.
  2. Clarification in Medical Negligence Cases: The ruling provides crucial guidance for handling medical negligence cases involving complex causal relationships, where it is impractical or impossible to pinpoint one cause of damage. It aligns with earlier cases such as Bonnington Castings Ltd v Wardlaw [1956], which also acknowledged the concept of material contribution in industrial disease context.
  3. Influence on Subsequent Case Law: The principles from Bailey have been applied and expanded in later cases, such as Williams v Bermuda Hospitals Board [2016], which further explored the boundaries of material contribution in medical contexts. Another case, Heneghan v Manchester Dry Docks Ltd [2016], used the Bailey principle in a context involving multiple sources of harm, emphasizing that defendants are liable only for the extent of their contribution.

Exam Questions and Answers

Below, you will find answers to questions that are most commonly asked based on this case.

What are the implications of this case for medical professionals’ liability insurance policies?

Bailey v Ministry of Defence impacts liability insurance by expanding potential claim scenarios to include “material contribution” to harm. This shift may cause insurers to modify policies, potentially leading to increased premiums. For example, in Fairchild v Glenhaven Funeral Services Ltd [2003], similar principles led to significant changes in insurance practices regarding asbestos-related claims.

How does the Bailey decision influence the handling of cases with unknown causes of medical complications?

Post-Bailey, courts may assign liability even when direct causation is uncertain, if a healthcare provider’s conduct materially contributed to the outcome. This approach was echoed in Sienkiewicz v Greif [2011], where material contribution was key in deciding asbestos-related cancer cases, influencing how cases with uncertain medical causation are approached legally.

What are the broader impacts of this case on patient safety and hospital procedures?

Following Bailey, healthcare settings may implement stricter safety protocols to mitigate risks of legal liability for “material contribution”. This preventative focus can lead to changes similar to those prompted by Montgomery v Lanarkshire Health Board [2015], which led to enhanced patient consent processes, aiming to reduce potential liabilities in patient care.