That argument is attractive to defendants because it sounds practical. It is also dangerous if pushed too far.
The familiar eggshell skull principle requires a defendant to take a claimant as they find them. The same logic applies to the mind. A person with psychological vulnerability is not entitled to less protection because they were more susceptible to psychiatric injury. If a negligent act causes a greater reaction in that claimant than it would have caused in someone else, the defendant cannot simply point to the vulnerability and walk away.
The law does not only protect the unusually resilient. That matters because personal injury claims are increasingly concerned with psychological impact as well as physical injury. Road traffic collisions, workplace accidents, assaults, clinical incidents and traumatic events can all produce psychiatric consequences. In some cases, those consequences are straightforward. In many others, they are complicated by prior vulnerability.
The real dispute is rarely whether the claimant had a history. The records may show that clearly. The real dispute is what changed as history is not a defence
A pre-existing psychiatric history does not automatically defeat a claim. That should not need saying, but it often does.
Insurers and defendants regularly examine GP records looking for earlier symptoms. Anxiety five years before the accident: Antidepressant medication, counselling, stress at work, previous episodes of depression, family difficulties and bereavement. The material may be relevant. Sometimes it is highly relevant however relevance is not the same as exclusion.
The existence of earlier psychological symptoms does not mean that later symptoms are unrelated to the accident. A claimant may have been functioning well before the index event despite a history of vulnerability. They may have been working, caring for family, maintaining relationships and living independently. The accident may then cause a significant deterioration. In that situation, the prior vulnerability forms part of the claimant’s baseline. It does not erase the consequences of the accident.
This is where psychiatric expert evidence becomes important. The expert is not asked simply to list diagnoses. They are asked to consider the trajectory of the claimant’s mental health before and after the event. What was the claimant’s pre-accident functioning? Were symptoms active or historic? Was treatment ongoing? Was there a pattern of relapse? Did the accident produce a new condition, an exacerbation of an existing condition or an acceleration of symptoms that were likely to emerge anyway?
Those questions decide the case far more often than the diagnostic label.
The mind has a baseline too.
Physical injury claims have long dealt with vulnerability. A claimant with degenerative spinal changes may suffer a worse outcome after an accident than a younger, fitter person. The court must then distinguish between damage caused by the accident and deterioration that would have happened in any event.
Psychological claims require the same discipline. A claimant may have a longstanding vulnerability to depression but no recent episode before the accident. Another may have been receiving active treatment at the time of the incident. Another may have had a history of trauma but stable functioning for years. These are not the same cases.
The expert’s task is to identify the baseline.
That baseline is not merely a list of previous diagnoses. It is a functional picture. How was the claimant living? Were they working? Were they socially engaged? Were they managing daily life? Were they taking medication? Had they required recent intervention? Were there stressors unrelated to the accident?
Without that baseline, causation becomes guesswork and the claimant with a psychological history may still have suffered a real and compensable worsening. Equally, a claimant with active pre-accident symptoms may not be able to attribute all later difficulties to the accident. The analysis must be more precise than either side often wants it to be.
Claimants want recognition of the change. Defendants want recognition of the history. The expert must consider both.
Eggshell does not mean blank cheque, the eggshell mind principle does not mean that every post-accident psychiatric symptom is recoverable.
This is the point often lost in claimant arguments. The defendant takes the claimant as found, but the defendant is not responsible for every difficulty the claimant has ever had or would have developed in any event. The compensation exercise still requires causation. It still requires proof. It still requires a distinction between accident-related harm and the underlying condition.
That distinction can be difficult.
Psychiatric symptoms rarely move in clean lines. Depression may fluctuate. Anxiety may worsen during litigation. Trauma symptoms may overlap with financial pressure, unemployment, family problems or physical pain. A claimant’s presentation may be influenced by multiple factors at once. The question is not whether the accident is the only cause. It rarely is. The question is whether the accident made a material difference to the claimant’s psychiatric condition and functioning. If it did, the vulnerability does not excuse the defendant. If it did not, the history may limit or defeat the claim.
This is why psychiatric reports need careful reasoning. It is not enough to say that symptoms followed the accident, so they were caused by it. Nor is it enough to say that the claimant had prior anxiety, so the accident did not matter. Both positions are too simple. The court needs a reasoned explanation of what changed, why it changed and how long that change is likely to last, the records tell the story, but not always neatly.
Psychological vulnerability is often documented across years of GP records, counselling notes, occupational health reports and medication histories. Those records can be revealing. They can also be misleading if read without context.
A single prescription for antidepressants may reflect a short-lived episode. Repeated consultations may suggest a more persistent condition. A gap in treatment may indicate recovery, but it may also reflect reluctance to seek help. A claimant may have significant symptoms without consistent medical attendance.
Experts must avoid both extremes: treating every historic entry as decisive and treating the records as irrelevant because the claimant now gives a different account.
Contemporaneous records matter because they show what was reported before litigation sharpened the dispute. They can help identify whether symptoms were present, absent, improving or deteriorating. They may also reveal alternative causes that need to be considered.
But records are not the whole truth. They are part of the evidence.
A good psychiatric medico-legal report will not simply recite the records. It will interpret them. It will explain the significance of prior symptoms. It will address inconsistencies. It will say whether the claimant’s account of deterioration is supported, undermined or only partly supported by the documented history, this is where expert evidence earns its value. Vulnerability is not weakness there is also a cultural problem in the way psychological vulnerability is discussed in litigation. Physical vulnerability tends to be treated as medical fact. Psychological vulnerability is too often treated as suspicion. A claimant with degenerative disc disease is seen as medically complicated. A claimant with anxiety or trauma history may be viewed as unreliable, fragile or prone to overreaction.
That distinction is unfair and clinically unsound. Psychiatric history does not make a claimant dishonest. It does not make symptoms imaginary. It does not mean the person was destined to break down regardless of the defendant’s conduct, it means the analysis is more complex.
The medico-legal system should be capable of handling that complexity. It should be able to recognise that some claimants are more susceptible to psychiatric harm without treating susceptibility as a defect in the claim. It should also be able to recognise when the accident has been overstated as an explanation for problems that were already active.
Both things can be true.
That is the uncomfortable territory psychiatric experts occupy, the expert’s role is not sympathy Psychiatric experts must be careful not to become advocates for vulnerability.
The fact that a claimant has suffered does not answer the legal question. The expert must remain focused on diagnosis, causation, prognosis and functional impact. They must consider alternative causes. They must distinguish history from deterioration. They must avoid converting compassion into opinion, the best reports are often the most disciplined. They set out the pre-accident position. They identify the post-accident change. They consider whether the change is consistent with the mechanism of injury and the surrounding evidence. They explain whether the claimant’s vulnerability made the psychiatric reaction more severe. They address what would probably have happened without the accident.
That final question is essential.
If the claimant would probably have experienced the same deterioration within a similar timeframe because of unrelated factors, the defendant should not be responsible for the whole picture. If the accident caused a deterioration that would not otherwise have occurred, or caused it earlier or more severely, that must be recognised.
The answer is rarely all or nothing. Psychological vulnerability is not a loophole. It is not a windfall. It is not a reason to assume dishonesty. It is a fact that must be analysed.
The eggshell mind matters because personal injury law is not designed only for people with perfect mental health histories. Many claimants enter litigation with prior trauma, anxiety, depression or stress. That is ordinary human reality, not an exception to be priced down automatically.
Defendants are entitled to challenge causation. They are entitled to examine records. They are entitled to argue that some symptoms were pre-existing or would have developed anyway. Those arguments may be valid, but they do not erase the central principle.
If a defendant’s negligence causes real psychiatric deterioration in a psychologically vulnerable claimant, the vulnerability does not reduce the wrong. It explains the consequence.
That is the discipline the courts, lawyers and experts must preserve. Not every psychological reaction is accident-related. Not every prior history defeats a claim. The task is to identify the difference.
