a. Factual causation
The first step is establishing a factual link between the defendant’s wrong and your damage. A simple practical test is called the “but for” test. It asks: Would you have suffered the harm “but for” the defendant’s wrongdoing? If the damage would have happened anyway (for example, due to a pre-existing illness), the defendant is not responsible.
When a defendant fails to act (an omission), the “but for” test becomes a counterfactual inquiry: What would have happened if the defendant had complied with his duty?
In one case, a man went to a hospital with stomach pains caused by arsenic poisoning, but the doctor negligently sent him home without a proper checkup. The hospital was not held liable because evidence showed the man had swallowed so much poison that he would have died anyway, even if the doctor had treated him perfectly. Because the mistake did not change the outcome, it wasn’t the “but for” cause.
In another case, an employer failed to provide a safety belt, but the claim failed because the evidence showed the experienced worker would likely not have worn it even if it were provided.
Material contribution to injury
Sometimes, many different things happen at once, making it hard to pin the blame on just one person.
If several factors work together to cause a single injury, the court may find a defendant liable if their specific wrong “materially contributed” to the injury. The wrong does not have to be the sole cause, provided it was more than a trivial factor in the damage.
In one case, the court found that both a natural illness (pancreatitis) and negligent medical care contributed to a patient’s extreme weakness, which led to her choking. Because the negligence made a “more than negligible” contribution to that weakened state, the defendant was held liable for the total injury.
Material increase in risk
In very specific cases involving industrial diseases like mesothelioma (caused by asbestos), the law is even more flexible. Because science cannot always pinpoint which specific exposure to asbestos triggered the cancer, the law allows the plaintiff to hold an employer responsible if he materially increased the risk of the disease occurring.
Loss of a chance: Can you sue for a “Maybe”?
In some cases, a person suffers harm because someone else’s negligence took away their opportunity to avoid a bad outcome or achieve a good one.
The courts treat “loss of chance” very differently depending on whether the plaintiff lost money or his health.
If a professional (like a solicitor) makes a mistake that causes the plaintiff to lose a chance to make money, the law is quite generous. Courts are generally willing to award damages if the plaintiff lost a “substantial chance” of a financial benefit. For example, if the plaintiff’s lawyer misses a deadline to file a lawsuit, the plaintiff can sue the lawyer for the “lost chance” of winning that case. Even if the plaintiff’s original case only had a 30% or 40% chance of winning, the court will often award the plaintiff 30% or 40% of what that case was worth. The plaintiff is not required to prove he was definitely going to win. The plaintiff just has to show the chance was “real and substantial" rather than a total guess.
If a doctor makes a mistake (like a late diagnosis) that reduces the plaintiff’s chance of recovery, the law is much stricter. If a doctor’s delay in diagnosis reduced the plaintiff’s chance of survival from 42% to 25%, the plaintiff generally cannot recover damages because he was already “more likely than not” to succumb to the illness.
However, even if the plaintiff cannot sue for the “lost chance” of a cure, he can still sue for direct harms caused by a delay, such as acceleration of suffering. For example, if a delay in diagnosis meant the plaintiff had to undergo more painful, aggressive chemotherapy than he would have needed if the cancer had been caught early, he can be compensated for that extra pain and suffering.
