The Silver Brief

When medical treatment goes wrong, the experience can feel confusing, frustrating, and at times overwhelming. You may be left with unanswered questions—was this avoidable? Should something have been done differently?

In England and Wales, understanding whether something has gone wrong in a legal sense often comes down to two key ideas: breach of duty and causation.

These terms may sound technical, but they are simply ways of answering two important questions:

• Was the care you received below an acceptable standard?
• Did that failure actually cause harm?

This guide explains both concepts clearly, so you can better understand what they mean—and how they apply in real situations.

You might also find this helpful: Duty of candour explained: Your rights as a patient in England and Wales

Medical negligence explained: Quick answer

Medical negligence occurs when:

• A healthcare professional owed you a duty of care
• That duty was breached (the care fell below acceptable standards)
• The breach caused avoidable harm

All three must be present. A poor outcome alone is not enough.

What is medical negligence?

Medical negligence (also called clinical negligence) happens when a healthcare professional provides care that falls below the standard expected, resulting in harm that could have been avoided. It’s important to understand that:

• Not all mistakes are negligent
• Not all poor outcomes are preventable
• Medicine involves risk, even with good care

To distinguish between an unfortunate outcome and negligence, the law uses a three-part test:

1. Duty of care
2. Breach of duty
3. Causation

Understanding duty of care

A duty of care arises as soon as a healthcare professional agrees to treat you. This applies whether you are:

• Visiting your GP
• Attending A&E
• Receiving hospital treatment
• Being treated privately

In practical terms, this means the clinician must provide care that meets a reasonable and accepted professional standard. In most cases, this element is straightforward and not disputed.

What is breach of duty?

A breach of duty occurs when the care provided falls below the standard expected of a reasonably competent professional in that field.

How is breach of duty assessed?

Courts in England and Wales use the Bolam test, which asks:

Would a responsible body of medical professionals have acted the same way?

Key points include:

• Peer comparison: A GP is judged against a competent GP, not a specialist consultant
• Professional support: If a reasonable body of clinicians would agree with the decision, it may not be negligent
• Logical scrutiny: Courts can reject medical opinions that are not logically defensible (Bolitho principle)

Examples of potential breach of duty

• Failing to refer symptoms that require specialist investigation
• Misreading or ignoring test results
• Delaying diagnosis without justification
• Prescribing incorrect medication or dosage
• Failing to explain significant risks before treatment

Not every mistake qualifies. The key issue is whether the care fell below accepted standards—not whether it was perfect.

What is causation in medical negligence?

Causation is about proving that the breach of duty actually caused harm. This is often the most challenging part of a case.

The “but for” test

The legal test is simple in principle:

Would the harm have occurred but for the negligence?

If the answer is yes, causation may not be established.

Examples of causation in practice

Example 1: causation established

A GP fails to refer a patient with a fracture. The delay leads to improper healing and corrective surgery.

• Breach of duty: failure to refer
• Causation: delay directly led to worse outcome

Example 2: no causation

A referral is delayed, but medical evidence shows the condition was already too advanced for treatment to make a difference.

• Breach of duty: yes
• Causation: no

Even where care was substandard, a claim may not succeed unless the harm can be linked to that failure.

Why breach of duty and causation both matter

Both elements must be proven.

• Breach without causation → no claim (no harm caused)
• Harm without breach → no claim (care met acceptable standards)

The law focuses on whether negligence made a real difference to the outcome.

The role of medical experts

Medical negligence claims rely on independent expert evidence (governed by CPR Part 35). Typically:

• Breach of Duty: Assessed by a peer expert in the same discipline as the defendant (the “like-for-like” rule).
• Causation & Prognosis: Assessed by relevant specialists to prove causation and determine long-term impact.

These experts review medical records and provide opinions on:

• What should have happened
• What actually happened
• Whether the outcome would have been different

Common situations involving breach and causation

These issues arise across many areas of healthcare:

• Delayed cancer diagnosis
  • Breach: failure to act on red flag symptoms
  • Causation: disease progression leading to worse prognosis
• Surgical complications
  • Breach: avoidable error during surgery
  • Causation: additional injury or recovery time
• Medication errors
  • Breach: incorrect drug or dosage
  • Causation: adverse reaction or lack of treatment effect
• Failure to refer
  • Breach: not escalating symptoms
  • Causation: delayed diagnosis or treatment

Do you have a potential claim?

You may have a potential claim if:

• Your care fell below acceptable standards
• There was a delay, mistake, or missed diagnosis
• Your condition worsened as a result
• Earlier or different treatment would likely have improved the outcome

A poor outcome alone is not enough—the key question is whether it was avoidable.

What evidence is important?

If you are trying to understand what happened, early evidence can help:

• Request your GP and hospital records
• Record what was said during consultations and make a note of the time you made the record
• Save letters, results, and correspondence
• Keep a diary to record how your condition and symptoms change over time

Medical records are often central to identifying both breach and causation.

What happens if you raise a complaint?

Many people begin with the NHS complaints process. This can:

• Provide explanations about decisions made
• Clarify whether guidelines were followed
• Identify communication issues
• Occasionally lead to an admission of error

While it does not provide compensation, it can be an important first step in understanding events. A medical negligence solicitor may recommend going through this process before beginning your compensation claim, as it may reveal further information and, possibly, helpful admissions.

Organisations that can help

If you need support or guidance, several organisations in England and Wales can help:

• Patient Advice and Liaison Service (PALS) – informal support within NHS hospitals
• NHS Complaints Advocacy – help with making formal complaints
• Healthwatch England – information about patient rights and local services
• Citizens Advice – general guidance on healthcare rights
• Action against Medical Accidents (AvMA) – specialist support for people affected by medical errors

These services are free and can help you better understand your situation.

See also: No Win No Fee medical negligence claims: Costs, risks & funding

Frequently asked questions

Medical negligence explained: In conclusion

Understanding breach of duty and causation can bring clarity to a situation that often feels anything but clear. These concepts are not just legal technicalities—they are tools for answering a fundamental question: Could this outcome have been avoided?

If you feel something was not right with your care, taking the time to understand these principles can help you ask informed questions, seek answers, and better understand what happened.

This guide is based on general principles of English and Welsh law, is intended for informational purposes only, and does not constitute legal advice or establish a professional relationship.