Expert Witnesses and the ‘Eggshell Skull’ Test

If you decide to make a personal injury (PI) claim, then you will most likely use an expert witness to testify as to your mental and physical state after the accident. This blog will give you an overview of medical professional and psychologist assessments, and whether you could be entitled to more compensation on the basis of expert witness reports. These assessments can also be used if your injury has triggered a health condition or exacerbated an existing one. This could make the party that has injured you pay out more in compensation, and is known as the ‘eggshell skull’ test.

GP Report

In most cases, your solicitor’s first point of contact when seeking a medical opinion on your injury will be a GP. It is best to have a GP who is not someone who has worked with you in the past or someone that knows you on a personal level – this could create a conflict of interest. In the recent English case of EXP v Barker [2015] EWHC 1289 (QB), expert evidence was nearly completely discounted because the expert witness did not state before the case came to court that he had previously worked with one the parties. Although your solicitor will usually ask the GP this whilst preparing your case, if there is some sort of co-working or personal relationship, make sure you let your solicitor know as soon as possible.

The written expert report will be prepared around six to eighteen months after your accident, and your GP or other experts relating to your case may have to testify in person if your case comes to court. Your solicitor will keep you and your doctor informed of possible trial dates.

Specialist Medical Professionals

An expert report from a specialist medical professional will be necessary depending on the nature and extent of your injury. For example, if you have had surgery on a broken leg, your solicitor may want to speak to the orthopaedic surgeon who operated on it.

Continuing with this example, the orthopaedic surgeon would likely talk the court through an X-ray of your injury to explain the damage. Your opponent will always be trying to pick holes in your argument to tip the balance of probabilities in their favour, so it is important that the expert witnesses testify regarding their expertise and do not provide an opinion that could be classed as conjecture.


A psychologist can give an opinion on your mental state after you have sustained an injury, as expert evidence to back up your personal injury claim. According to psychologists writing in the Solicitors Journal:

A robust psychological opinion is based on five sets of data: the claimant's self-report of history and complaints, the expert's observation of the presentation and mental state of the claimant, any objective psychological or behavioural testing data, the claimant's medical records, and any other collateral sources of information.

To make sure their opinion is robust, the psychologist will at first look at your GP visits before your accident to determine any issues. They will also look at your records and medical opinion to establish pre-existing psychological injury, or PEI:

A key time frame is the 12-month period immediately prior to the index accident. Larger time frames [before the accident] may point to a predispostion …but the 12-month period … may significantly affect the causation and hence the resulting quantum decision.

Looking at PEI must be helpful rather than detrimental to your case, and can be used alongside the ‘eggshell skull’ test. This is used to evaluate causation, your opponent’s liability, and is ultimately a way for apportioning damages.

The ‘Eggshell Skull’ Rule

The ‘eggshell skull’ rule means that the person who has injured you should be liable for all the damage you have sustained.

This is even if the incident that caused your inury has accelerated an undiagnosed pre-existing medical condition, if the incident has made the injury worse through the fault or negligence of the other party, or if the incident made a previously treated condition come back.

A good example of this is the English case of Smith v Leech Brain & Co [1962] 2 QB 405. In this case, a factory worker’s lip was burned by molten metal. The worker developed cancer where he had been injured, and the defendant was held to be liable for all harm caused, even though the cancer was not yet diagnosed. This is because it was foreseeable that such an injury could lead to cancer developing.

The Eggshell Skull Rules: ‘Thin Skull’ and ‘Crumbling Skull’

There are two categories applied to injuries falling under the ‘eggshell skull’ test: a ‘thin skull’ and a ‘crumbling skull’.

The ‘thin skull’ rule applies if you do not have any evidence of significant symptoms and you are seen as being vulnerable. 

On the other hand, your injury will fall into the ‘crumbling skull’ category if your health has significantly deteriorated before gaining the injury or immediately after getting the injury.

If you are within the ‘thin skull’ category, then the person that injured you will be liable for costs associated with your injury. If your injury is categorised as ‘crumbling skull’, then the person that injured you will be considered to be liable for the events which caused the injury to get worse.

What Can I Do To Help My Case?

Make sure that you document your accident and any conversations with medical professionals, and ask them if they can help in your personal injury case - ideally before you brief your solicitor. 

The ‘eggshell skull’ test is not always consistent in its application and can be quite confusing in its approach. It is a good way of illustrating different degrees of injury and how the person that has injured you is liable for your injuries, especially if you imagine your injury to be as fragile as an ‘eggshell’ that has been exacerbated by the fault of another.

What Can Lawford Kidd Do To Help Your Case?

If you have suffered an injury in an accident that wasn’t your fault, we can help. We can help you secure an expert witness to provide evidence concerning the severity of your injury. Furthermore, even if you decide to settle out of court before the case comes to trial, you may even be able to claim the costs of instructing expert witnesses from the other side. It was recently decided in the Scottish case of DM v Lothian NHS Board [2015] CSOH 89 that the pursuer could recover the cost of instructing five expert witnesses from NHS Lothian, even though she had settled out of court.

We offer a free initial consultation and are in Legal 500’s top three Scottish personal injury firms. To start your claim, call us free today on 0808 163 7219 or fill out our online form, which you can find here.

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