When to Use Expert Evidence in a Business Dispute

In commercial litigation, not all disputes turn on straightforward facts alone. Some matters raised in business claims involve complex technical, financial, scientific, or professional issues that fall outside the normal knowledge and experience of judges. In such situations, parties may seek to rely on expert evidence to help the court understand specialised matters and decide the case fairly. Expert evidence can be decisive in disputes involving valuations, technical specifications, accounting matters, or industry‑specific standards.

However, the courts do not allow expert evidence as a matter of course. There are strict rules and procedures governing when it can be used, why it is needed, and how it should be presented. This article explains the circumstances in which expert evidence is appropriate in business disputes, the legal framework for its use, and the practical considerations for litigants.

What Is Expert Evidence?

Expert evidence is opinion evidence provided by a person with specialised training, qualifications or experience in a particular field. The purpose of expert evidence is to assist the court in understanding issues that are beyond the ordinary knowledge of judges and solicitors.

Examples of commercial issues where expert evidence is commonly used include:

• Valuation of businesses or shares
• Complex financial accounting or taxation issues
• Technical engineering or construction specifications
• Intellectual property valuation or infringement analysis
• Digital forensics or information technology systems
• Professional standards in fields such as surveying or medicine

Expert evidence is generally presented in the form of a written report and, if permitted by the court, may also include oral testimony at a hearing or trial.

Legal Framework: When Expert Evidence Can Be Used

In England and Wales, expert evidence in civil litigation - including business disputes - is governed by Part 35 of the Civil Procedure Rules (CPR) and the associated Practice Direction 35. These rules set out when expert evidence is permitted, how it must be prepared, and the duties of experts and litigants.

Key legal principles include:

Court Permission Is Required

No party may rely on expert evidence without the permission of the court. Before an expert report can be submitted or an expert called to give evidence, the party intending to use that evidence must seek the court's approval.

Relevance and Necessity

Under CPR 35.1, expert evidence should be limited to that which is reasonably required to resolve the proceedings. This means it should address a real dispute in the case and provide assistance the court could not obtain from the factual evidence alone.

When Expert Evidence Is Reasonably Required

Expert evidence is most useful where the court would not be able to decide an issue fairly and accurately based on the evidence of the parties alone. Typical situations include:

Highly Technical or Specialist Issues

Where the facts involve specialised technical knowledge - such as complex mechanical processes, software systems, chemical compositions, or industry‑specific standards - the court may need expert evidence to understand the relevant principles and form its own view.

For example, in construction disputes, a structural engineer's report may be needed to explain whether works complied with technical specifications.

Complex Financial Analysis

Business disputes often involve disagreements over financial matters such as:

• Calculation of loss of profit
• Valuation of businesses or shares
• Assessment of financial projections
• Interpretation of complex accounting standards

In these cases, an accountant or financial expert can help clarify the issues and provide reasoned analysis that the court can rely on.

Professional Standards or Practice

Where a dispute concerns whether a professional met required standards - such as in allegations of negligence by consultants, surveyors, or other advisers - it may be necessary to call on an expert qualified in that field to explain what standard is expected and whether it was met.

Timing and Permission

Parties should consider expert evidence early in litigation, especially where the issues likely to arise are foreseeable before proceedings are issued or shortly after.

In some instances, the court will direct parties at a case management conference to state whether expert evidence is needed, identify the issues that require expert opinion, and seek permission to rely on that evidence.

If one party believes expert evidence is necessary while the other does not, permission may be sought contemporaneously with the filing of evidence or at specific stages of the proceedings, including before interim applications.

Types of Expert Evidence

Single Joint Expert (SJE)

Where both parties agree or the court directs, a single joint expert may be appointed. All parties share the cost and receive the same expert opinion. This can reduce costs and narrow areas of disagreement.

Separate Experts for Each Party

In more complex disputes or where parties disagree on the issues to be addressed, each side may obtain its own expert evidence. The court's permission is still required, and reports are usually exchanged so that each party can challenge the other's expert opinion.

The Role and Duties of Experts

Experts have specific duties designed to preserve the integrity of their evidence:

• They must assist the court impartially, not act as advocates for the party instructing them.
• Their opinions must be independent and unbiased, considering all relevant facts, even those unfavourable to the instructing party.
• The expert's report must include the instructions they received, the facts they relied on, and any assumptions or limitations affecting their opinion.

These duties are reinforced by the Practice Direction and guidance from the Civil Justice Council, ensuring that expert evidence meets professional and legal standards.

Practical Considerations for Using Expert Evidence

Cost and Proportionality

Expert evidence can be expensive, particularly where multiple experts are involved. Courts will consider whether the cost is proportionate to the value and complexity of the dispute, and may limit the scope of expert evidence accordingly.

Early Identification of Issues

Identifying early that expert evidence may be needed allows parties to incorporate it into the litigation timetable and seek the necessary court permission in good time, reducing the risk of delays or objections from the opposing party.

Agreeing on Issues and Scope

Where possible, parties should seek to agree on the issues requiring expert evidence and the scope of that evidence. Timely agreement can reduce costs and help the court manage the case more effectively.

Risks of Inappropriate Expert Evidence

If expert evidence is introduced without court permission or on issues that are not genuinely technical or in dispute, the court may:

• Exclude the evidence
• Limit reliance on it
• Penalise the party that introduced it

Improper use of expert evidence may also result in adverse cost orders if the court considers it unnecessary or disproportionate.

Common Questions About Expert Evidence in Business Disputes

Is expert evidence always required in commercial cases?

No. Expert evidence is only used where it is reasonably necessary to resolve a dispute. In many commercial cases, witness evidence and documentary evidence will be sufficient.

Do experts have to appear in court?

Not always. Expert evidence is usually presented first in written reports. Oral testimony may be given if the court permits or directs it.

Can the court require a party to use a joint expert?

Yes, in appropriate cases the court may order that a single joint expert be used to reduce cost and avoid duplicative evidence.

Key Takeaways

Expert evidence plays an important role in commercial disputes when the issues involved are technical, specialised, or beyond the ordinary knowledge of judges. In England and Wales, expert evidence must be permitted by the court under CPR Part 35 and Practice Direction 35, and is only allowed where it is reasonably required to resolve the proceedings. Expert witnesses owe an overriding duty to assist the court with independent, unbiased opinion on matters within their expertise.

Common scenarios that warrant expert evidence include valuation disputes, complex financial analysis, technical compliance issues, and assessments of professional standards. Parties should identify the need for expert evidence early, consider cost and proportionality, and seek to agree on the scope and issues where possible. Misuse or unnecessary expert evidence can be costly and may be rejected by the court.