Medical Negligence

What is the date of knowledge in clinical negligence?

Updated: 25th May 2023
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Medical Negligence Solicitor, Co-founder and Managing Partner - LLB (Hons) University of East Anglia, 1989

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If you or a family member is harmed as a result of clinical negligence, in most circumstances you should assume you will have a three-year limit to make a claim.

This deadline is in place to balance out the rights and interests of both the claimants and the defendants in every case. The longer the span of time between an act of negligence occurring and the claim being brought, the greater the chance that essential evidence and witnesses will not be available.

For claimants, this may hurt the possibility of their claim being successful, or restrict the amount of compensation they are granted. For defendants, it can mean the loss of evidence that supports a defence. A lack of a time limit would also mean that a defendant is never certain that a claim may not appear, even from events many years earlier.

However, while it is always safest to assume you have three years to make a claim, there are exceptions to this rule:

  • Claimants under the age of 18 have until their 21st birthday to make a claim
  • If the claimant is mentally incapacitated at the time of the negligence occurring or as a result of the negligence, there is no limit on when they can make a claim
  • If the claimant passes away within the three-year time limit for the claim to be brought, the three-year limit begins anew at the date of their death
  • Where a person dies as a result of their treatment, dependents who are under 18 at the time of that death have until 3 years after their 18th birthday to bring a claim

These time limits apply where it is easy to see that an action or failure to act has caused or led to an injury. However, where the injury is hidden or only occurs some time after the event, then the 3-year time limit will run from date of knowledge – which is the topic of this article.

This rule recognises that, in certain circumstances, a person may not become aware that they have been affected by an act of negligence until beyond the three years after the act took place, and that this should not deny them the chance to make a medical negligence claim.

What is the date of knowledge?

The date of knowledge is defined in section 14 of the Limitation Act 1980. To summarise, this states that claimants have a three-year time limit to make a claim from the date when they gain knowledge of the injury that they have suffered.

This is because a claimant may not immediately be aware of any harm they have suffered, especially if an illness/injury has not been properly diagnosed or treated. It might not become apparent to them until they encounter further symptoms at a later date and undergo investigations that find the true cause of their problems.

Section 14 of the Limitation Act 1980 states that a claimant will only be deemed to have knowledge such that the time limit starts to run once:

  • They are aware of having a significant injury
  • They are aware that the injury is attributable to the act or omission of a medical professional
  • They know the identity of the defendant

However, it is important here to note that the date of knowledge is not necessarily when the person actually has this knowledge, but the point at which they could reasonably be expected to know there was an issue based on their circumstances.

The test for date of knowledge is determined by an independent Judge on a case-by-case basis, looking at when it would have been reasonable for the claimant to suspect and then begin investigations.

When might the date of knowledge apply?

In most circumstances, the date of knowledge will be applied in instances where the harm caused by an act of clinical negligence is hidden or does not arise until a later date. This can occur in situations where:

  • A condition is misdiagnosed and the patient is told that there is nothing wrong
  • A failure to provide treatment to the condition the patient is affected by
  • The patient is treated for another condition than the one they actually have, leaving the cause of their initial complaint untreated

For example, imagine a patient that undergoes a cervical smear test and is told that everything is normal. Four years later the patient has developed more noticeable symptoms for which they undergo tests, which reveal that they have now developed cervical cancer.

If the smear test was misreported and proper reporting would have resulted in an early diagnosis, which could have been treated and cured, the cure may now no longer be possible and/or the treatment required is much more onerous than the delay has significantly altered the prognosis for that person.

However, as it had been over three years since this test took place, this means making a claim would be impossible without the date of knowledge exception.

This can apply in any circumstance where there has been a failure to identify a condition, a failure to refer a patient for tests or for a more specialist opinion, or a failure to provide appropriate treatment. In each of these situations, the patient has put their trust in the healthcare professional and that is the cause of the delay.

How is the reasonable date of knowledge determined?

As noted earlier, the deemed date of knowledge for a claimant may not be the same as the date they actually become aware of the issue.

Instead, a Judge will determine, based on the unique circumstances of the case, the date by which it would have been reasonable for the claimant to suspect that there was something wrong with the treatment and begin investigation into that possibility.

This is set out in section 14(3) of the Limitation Act 1980 which states that:

For the purposes of this section a person’s knowledge includes knowledge which he might reasonably have been expected to acquire –

(a) from facts observable or ascertainable by him; or

(b) from facts ascertainable by him with the help of medical or other appropriate expert advice which it is reasonable for him to seek

A Judge will therefore consider the evidence and medical advice presented to them about when the claimant in their situation should have been reasonably expected to know they had grounds for a claim. This will be influenced by factors such as:

  • The timeline and severity of symptoms they developed following the initial incident
  • The claimant’s personal circumstances and how these may have caused a delay
  • Whether the claimant had sought out a second opinion from another medical professional following the initial diagnosis

The claimant’s solicitor will be tasked with providing evidence to justify the delay in making this claim. This means that, if a claimant fails to act on what a Judge considers reasonable suspicion of the negligence they suffered, they could potentially see their date of knowledge be positioned too far beyond the three-year limit to make a claim.

Why you should always make a claim as early as possible

It is important to emphasise that the Limitation Act is a defence of a medical negligence claim and not a bar. This means that, if the court considers it right that a claim is brought outside of the three-year limit, or that a defendant agrees to the claim proceeding, it is at the court’s discretion as to whether it is allowed to proceed or not.

One of the things that a court will consider when deciding whether to exercise its discretion in this way is what prejudice there will be to the defendant if limitation is extended. For instance, witnesses may die and their memories will fade. Physical evidence may deteriorate or be lost.

However, as medical negligence claims are often largely reliant on the medical records and these have become more universally digitised in recent years, loss of evidence is less likely to be a problem, which means that there one less reason for the court to refuse to exercise its discretion to extend time than in the past, when physical records might well have been misplaced or destroyed in the time since the incident occurred.

However, although this discretion is available, it is a discretion and cannot be relied upon. Therefore we urge you to make a claim as soon as it is possible if you have been affected by medical negligence. This is because, as discussed earlier, the longer you take to make a claim, the more problematic it can be to achieve a successful result:

  • Evidence might be lost or degrade to the point of being unusable
  • Key witnesses and defendants may pass away or forget the detail of what occurred or become incapacitated
  • It takes a substantial amount of time for your solicitor to gather the required evidence, which might be difficult if you start proceedings near the end of the three years

Whether you know immediately that you have suffered an injury, or it does not become apparent until a later date, once you become aware it is essential that you take action early to give your claim the best chance at success.

Speak to the true specialists in clinical negligence

We hope that this introduction to the date of knowledge offers reassurance that it is always worth seeing if you may have to make a clinical or medical negligence claim for compensation, even if your initial inquiry is several years after the incident occurred.

While these exceptions exist, we encourage you to bear in mind two key pieces of advice from this article:

  1. Always presume that you have three years to start your claim.
  2. Make your claim as soon as possible to improve its prospects.

At Gadsby Wicks, our team of expert medical negligence solicitors are ready to take on your claim at any time, dedicating the expertise and resources necessary to build a strong, compelling case that secures the compensation and justice you deserve.

Where required, we will also go to great lengths to defend your right to make a claim where we believe there is reason to do so, providing evidence of your later date of knowledge and petitioning for extensions from the court.

Contact us today to speak with the true specialists in medical negligence.


All content contained within this article is meant for general information only – this should not be treated as a substitute for medical advice from your doctor or another healthcare provider. If you require legal advice specific to your situation, please contact our team directly.

Gadsby Wicks is not liable for any diagnosis made from the content of this article, nor does it endorse any service or external site linked to within the article.

Always consult your GP if you are concerned about your health and wellbeing, or speak to us if you require legal advice.