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What is causation?
The burden of proving every aspect of a personal injury claim lies with the claimant. In other words, the claimant must prove their claim; the defendant does not have to disprove it.
As a claimant, one of the most challenging issues can be proving ‘causation’, i.e. that the accident was the cause of the injury and other losses. There are two parts to the causation test. The claimant must prove that:
- the defendant’s breach of legal duty (i.e. the accident or other triggering event) caused or contributed to their injury and resulting loss; and
- the injury and loss suffered were not too remote or unforeseeable.
The concepts of remoteness and foreseeability ensure that frivolous claims are unsuccessful.
In considering causation, the court applies the ‘but for’ test, i.e. ‘but for’ the accident, would the claimant have suffered the injury and loss?
Causation in a CRPS compensation claim: Expert evidence
A claimant satisfies the ‘but for’ test with evidence, which takes various forms. For example, witness statements provide evidence on disputed factual matters. However, proving whether and to what extent the accident caused the claimant’s injuries requires expert opinion evidence from one or more people that the court accepts as having relevant medical expertise.
A medical expert’s sole duty is to assist the court on matters within their area of expertise. So, for example, an orthopaedic surgeon must limit their opinion evidence to musculoskeletal matters.
Chain of causation
Many liken causation to the links in a chain. Each successive link may require different evidence, and the chain of causation must remain unbroken. Again, this is best illustrated by way of an example. A claimant requires expert orthopaedic evidence to prove their accident at work caused their wrist fracture. In turn, they will also need the expert opinion of a rheumatologist or a pain medicine specialist if, following the wrist fracture, they have developed complex regional pain syndrome (CRPS) in the same limb. The pain expert will opine whether, on the balance of probabilities, the wrist fracture caused the CRPS.
Causation in a CRPS compensation claim
A common mistake solicitors make is neglecting to prove every link in the causation chain. So, a person suffers a fractured wrist in an accident at work and, shortly afterwards, develops CRPS. Even though the original wrist fracture has fully recovered, the claimant must still prove with expert orthopaedic evidence that the cause of the fracture was the accident at work.
That may sound unnecessary, but say a review of the claimant’s medical records reveals an A&E attendance for a painful wrist following a fall at home on the day before the accident at work. In that case, it’s then a matter for the orthopaedic expert to assist the court on the relative involvement of each incident.
Thorough investigation is essential
You can see that causation in a CRPS compensation claim is complex and finding a claim without at least one causation problem to overcome is rare. A thorough early investigation by the solicitor is crucial in anticipating causation issues. That begins with obtaining and carefully reviewing a complete set of the claimant’s medical records. They should also take a detailed statement from the claimant and anyone else whose factual evidence might impact causation.
A solicitor is not a medical professional and certainly not a specialist in orthopaedics, pain medicine, etc. However, claims involving CRPS and other forms of chronic pain are always among the most difficult to prove causation. Therefore, any solicitor undertaking this work must have a sound working knowledge of the medical issues involved.