What a claimant must prove
In a claim for clinical negligence, a Claimant must broadly prove two things. First that an error has occurred in their treatment. Second, the Claimant must prove that the error has caused them to suffer a loss i.e. a physical and/or psychological injury. This is known as Causation and is often a difficult hurdle in clinical negligence claims.
To prove the second limb of this test, that an error has caused the Claimant loss, the Claimant must prove on the balance of probabilities what would have happened but for the negligence compared to what did in fact happen. For instance, in the case of a delay in diagnosing cancer, the Claimant must prove what treatment they would have received, as well as what their likely long term outcome would have been compared to what their long term prognosis is given their delay in treatment.
The first difficulty is that in almost all cases, the Claimant will have a condition that would have required some treatment in any event. Using our example in a case of delayed diagnosis of cancer, there would likely been some radiotherapy and/or chemotherapy and/or surgery that would have been needed to treat the malignancy. This is not caused by the breach of duty. However, if more extensive treatment would have been needed, or indeed whether the chance to treat the malignancy to allow for a better outcome had passed, then causation becomes clearer.
The comparison between outcomes is for the Claimant to prove and not for a Defendant to disprove. But how can the Claimant prove what would have happened otherwise? We can never know for certain what would have happened if the Defendant had not made a mistake and treatment had not been delayed. In a way, Defendant’s negligence has already put the Claimant at a disadvantage.
Causation case study
The recent Court of Appeal case of Schembri v Marshall  EWCA Civ 358 gives litigants useful guidance on how the courts will interpret the issue of causation. It acknowledges the difficulties a Claimant may have proving what would have happened if treatment had not been delayed and accepts that a Claimant may not have to prove exactly what otherwise would have happened.
Schembri involved a delay in diagnosing a pulmonary embolism (“PE”). The Claimant’s wife, Mrs Marshall, had attended her GP with symptoms of chest pain, breathlessness and a history of previous PE. The Defendant GP did not recommend Mrs Marshall go to hospital and unfortunately, she returned home only to collapse hours later. Despite paramedics’ best efforts, Mrs Marshall sadly passed away.
There was no dispute between the parties that the GP should have referred the Mrs Marshall to hospital. A failure to do so fell below a reasonable standard of care.
However, the parties did argue over what would have happened otherwise, i.e. what would have happened had Mrs Marshall been referred to hospital as it was agreed she should have been. The point in dispute is whether Mrs Marshall would have been given treatment that would have avoided the devastating outcome that was seen.
On appeal, the Defendant argued that the Claimant had failed to positively establish the mechanism by which the deceased would have been saved. As mentioned above it is for the Claimant to prove the breach caused loss i.e. what additional injury she suffered from as a result of the breach. She would have required some treatment for the PE in any event, regardless of the breach. The Defendant argued that it was incumbent on the Claimant to prove which treatment or treatments would have saved Mrs Marshall. This was regardless of the overwhelming statistical evidence that the vast majority of patients in hospital with PE do in fact survive. In short, The Defendant did not have to prove it did not make a difference – the Claimant had to prove it did.
The courts disagreed with the Defendant’s position. The courts made a point of acknowledging the difficulties faced by Claimants to prove what would have happened had treatment not been delayed. The actual outcome was unknown due to the Defendant’s breach of duty.
The courts had to resort to taking an overall look at the case and the evidence available, both of the specific condition and health of the Claimant, as well as the available medical statistics of similar cases. Although the Claimant could not prove exactly what would have happened had Mrs Marshall’s treatment not been delayed, given the large numbers of unknowns presented by the delay in diagnosis, the courts took the view that it was simple common sense to conclude the delay had caused Mrs Marshall’s death. In this writer’s view, it was only right to do so.