Expert Evidence


A rough guide to Personal Injury and Clinical Negligence Litigation for Professional Indemnity Lawyers

Clinical negligence and complex personal injury litigation are unusual in terms of the cost, complexity and range of expert evidence required. The client’s reliance on that evidence is absolute. If the expert evidence is not supportive, the claim will almost always have to be discontinued, or will fail at trial. The cost of obtaining expert evidence can be painfully high1.

The most serious cases aside2, the three year limitation period and waiting times for good experts place significant demands on solicitors working in this area. Mistakes are common.

There are no special rules3 for expert evidence in PI and clinical negligence claims. However, in practice the experts’ role in these areas is different from other areas of the law.

Which expert to instruct and when?

The apparently simple task of instructing experts is often far from straightforward. A range of decisions will need to be made. Which specialisms should be instructed first? Is a preliminary report or a full report required in the first instance? If the latter, what is the state of the witness evidence? Are all the relevant medical records available? If not, what are the risks of delaying instruction to obtain these?

For the solicitor, the starting point is always to investigate liability and causation. There is no point spending good money investigating quantum until there is supportive evidence on breach and causation. In a complex case, much of the time pre-issue is spent on these issues4 with little effort spent on quantification.

Important decisions have to be made about how much evidence to obtain before the Court has agreed such evidence can be relied upon5. Is it better to risk having to amend the case, or spend money on evidence the Court deems unnecessary or disproportionate?6

Cases frequently develop in unpredictable ways and experts often suggest additional reports are required7. Decisions have to be made about whether those reports are really needed or will be worth the cost8.

Assuming that the correct specialisms have been identified, who should be selected? Cost, reputation, experience in the precise issue at stake and past performance are all relevant considerations.

Coordinating expert evidence

Conferences between the lawyers and the experts are essential in a case of any complexity. Conferences allow expert evidence to be refined, gaps to be plugged, experts to understand how their colleagues’ views affect their own and how the witness evidence affects the interpretation of the medical records. Done properly, there is an iterative process by which experts’ reports are amended to reflect the developing evidence in the case. This takes time. It is also often expensive.

Agendas for expert meetings are invariably used in clinical negligence cases, but rarely in personal injury. Preparing agendas that carefully address all the issues is painstaking.

Assessment of Expert Evidence

It is rare for experts to agree completely. When expert evidence is received from the other side, this must be passed on for comment.

A key task for the lawyers is to assess where the merits of the expert evidence lie and advise the client appropriately. There is frequently a body of scientific literature on the expert issues. A solicitor should ensure that the expert reviews the relevant literature and tests whether the expert’s evidence is likely to stand up to scrutiny.


There are a range of funding options, but legal aid and ATE insurance with recoverable premia may be available to meet the costs of expert evidence.

Hailsham Chambers specialises in clinical and professional negligence with many members having considerable experience of both areas and frequently acting in claims for failed personal injury or clinical negligence litigation.

  1. It is not unusual to see approved budgets (at least on the Claimant’s side) in the region of £300,000 for a clinical negligence claim worth in the region of £1m. The costs of dealing with the experts (instruction, reports, joint meetings, conferences, attendance at trial) can account for around half that expenditure.
  2. Claims by children injured at birth and those who have lost capacity as a result of their injuries are not subject to the three year limitation period.
  3. Save, perhaps, the rule that a condition and prognosis report must be served with the Particulars of Claim: CPR 16 PD 4.3
  4. See the comments of Spencer J at [49] of Mark v Universal Coatings & Services Limited [2018] EWHC 3206
  5. The usual rules in Part 35 apply: the Court grants permission to rely upon expert evidence.
  6. In practice, expert reports are often obtained from experts whose evidence is not used because their evidence is not helpful. More difficult are the cases where the evidence is likely to be useful, but on a relatively small issue in the case.
  7. A common example would be an orthopaedic surgeon expressing concern about the radiology reports in the medical records and suggesting a radiologist should be instructed.
  8. Note that the cost is usually far more than the cost of the expert preparing the report. There is also: solicitors’ costs of instruction, the cost of the other side’s expert preparing a report, costs of attendance at a conference (or two), costs of drafting and responding to agendas for joint meetings, costs of attendance at trial.