Proving Causation In Medical Negligence Cases – A Closer Look

Causation In Medical NegligenceIn order to succeed in a medical negligence case, a Claimant must prove the following:

  1. That the Defendant owed the Claimant a duty of care;
    – In a claim involving medical negligence, this test is satisfied because a healthcare provider always owes their patient a duty of care when providing treatment.
  2. There was a breach of the duty; and
  3. Causation.

All three of the above elements are essential for a successful medical negligence claim.

Causation in medical negligence claims

When it comes to establishing causation, often it is not straightforward. One reason for this is that we are looking at the hypothetical question of what would have happened had there not been a breach of duty. Many medical negligence cases also involve Claimants who were ill before the treatment and therefore proving causation can be complex.

The ‘but for’ test

The standard test for proving causation is the ‘but for’ test, e.g. ‘but for the negligent medical treatment, the injury to the Claimant would not have occurred‘.

Therefore, the Claimant must show their injury was caused by the negligence and that the loss or damage they suffered would not have occurred had the negligence not occurred.

If the injury, loss or damage would have occurred in any event, despite the negligence then the medical negligence claim will fail.

It is for the Claimant to prove this ‘on the balance of probabilities’. This means it must be proved that it is more than 50% likely the injury was caused by the alleged negligence.

The material contribution test

The ‘but for’ test can clearly cause problems for Claimants in cases where there may be multiple causes of the injury.

In such cases, it is appropriate for a modified test to be applied, the Court should be asked to consider whether the alleged negligence made a contribution to the injury and if the contribution it made to the injury was ‘material’. This is known as the material contribution test.

In order to succeed under this test it must be shown that:

  • The negligence contributed to the damage/injury itself and did not just cause an increased risk of injury/loss, save for in exceptional cases.
  • The contribution must be material – this means more than negligible and It is for the Court to choose the measure of materiality.
  • There must be no alternative complete cause of the injury – this means the material contribution test is only appropriate when there are multiple causes of the injury and only one cause cannot be established.


There are therefore two ways that causation can be established in a medical negligence case:

  1. To prove that the Claimant would not have suffered the injury but for the negligence of the medical professional on the balance of probabilities.
  2. To prove that the negligence made a material contribution to the injury on the balance of probabilities.

It is a commonly held misconception that in order to succeed with a medical negligence compensation claim, it is enough if the Defendant admits that there was a breach of duty of care, but there is much more to a medical negligence claim than this. All three elements must be proven for a claim to succeed – duty, breach and causation.

It is fair to say that the causation element of a claim in medical negligence claim is often the more difficult to prove.

Causation in medical negligence claims is complex as there can be instances where injury, loss or damage can take place even if negligent treatment had not occurred. When making a claim a specialist and experienced legal team is vital to thoroughly understand the issues and determine whether causation can be established.

How can Nelsons help?

Georgina Sheppard is a Paralegal in our expert Medical Negligence team, which is ranked in tier one by the independently researched publication, Legal 500.

At Nelsons, we have an experienced team of solicitors across our Derby, Leicester and Nottingham offices, who are always happy to discuss the circumstances of your claim and advise you on whether you are likely to be successful.

Please call 0800 024 1976 or contact us via our online form for more information.