Breach and Causation: The Role of a Nurse Expert Witness Explained

In clinical negligence litigation, two elements determine whether a claim succeeds: breach of duty and causation. The role of a nurse expert witness is central to both.

While it is often straightforward to identify that care could have been improved, the legal test is far more nuanced. Courts require clear, evidence-based analysis of whether care fell below a reasonable standard - and whether that failure caused harm.

This article explains how a nurse expert witness approaches these questions in practice.

Understanding breach of duty

Breach of duty considers whether the care provided met the standard expected of a reasonably competent practitioner.

For a nurse expert witness, this involves assessing care against:

• Accepted clinical practice

• Relevant guidelines and policies

• Real-world working conditions

Importantly, the standard is not perfection. The question is whether a responsible body of nursing professionals would have acted in the same way.

Real-world practice vs hindsight

A key part of the nurse expert witness role is resisting hindsight bias. Care is often delivered in busy, pressured environments with incomplete information. Decisions must be made quickly, and not all risks can be eliminated.

Experts therefore assess:

• What was known at the time

• What options were available

• Whether the chosen course was reasonable

An adverse outcome does not automatically indicate a breach of duty.

Common areas of alleged breach

In practice, nurse expert witnesses are frequently asked to consider:

• Failures in monitoring or observation

• Inadequate risk assessments

• Delayed escalation

• Poor documentation

Each must be analysed in context, rather than in isolation.

Causation: the more difficult hurdle

Even where a breach is identified, the claim will fail without causation. Causation asks whether the breach actually caused the harm complained of. This is often the more challenging aspect of the analysis. A nurse expert witness must consider:

• whether earlier intervention would have changed the outcome

• whether the harm would have occurred anyway

• whether other factors were involved

The importance of logical analysis by a nurse expert witness

Courts require causation opinions to be logical, evidence-based, and defensible. A nurse expert witness cannot rely on assumption or speculation. Instead, they must explain the likely clinical progression, identify points where intervention may have altered events and assess the probability of a different outcome.

Where this cannot be established, causation is unlikely to succeed. One of the most common misconceptions is that identifying a failure automatically leads to liability. In reality, many claims fail because, although care was imperfect, it did not cause the injury. A nurse expert witness plays a crucial role in clarifying this distinction, ensuring that claims are assessed on evidence rather than outcome alone.

Why this matters

The role of the nurse expert witness in analysing breach and causation is fundamental to clinical negligence litigation.

Their opinion helps determine whether a claim is viable, defensible, or unlikely to succeed. It also ensures that care is judged fairly, based on real-world standards rather than retrospective criticism.

For legal professionals and healthcare providers alike, understanding this process is essential. It is not enough to show that something went wrong - it must be shown why it went wrong, and whether it could have been avoided.