The forensic expert's opinion as evidence in court: its legal force

Many people are convinced that a forensic expert’s opinion is the final “verdict” in a case — something the court is bound to accept without question. The law takes a different view: the opinion is a full-fledged source of evidence, but it is not “more important” than the others, and the court weighs it together with all the case materials. Let me explain the legal force a forensic expert’s opinion actually carries, when a court may reject it, and where the limits of my competence as a forensic economic expert lie.

The expert opinion is an independent source of evidence

The first thing to understand is that a forensic expert’s opinion is a separate, self-standing type of evidence, expressly provided for by procedural law. In criminal proceedings the opinion is one of the procedural sources of evidence (Article 84 of the Criminal Procedure Code of Ukraine, the KPK) and is regulated in detail by Article 101 of the KPK. In civil procedure the expert opinion is named among the means of proof (Article 76 of the Civil Procedure Code, the TsPK), and the requirements for its content are set out in Article 102 of the TsPK. In commercial proceedings the corresponding role is played by Article 98 of the Commercial Procedure Code (HPK), and in administrative proceedings by Article 104 of the Code of Administrative Procedure of Ukraine (KASU) — the last being especially relevant, since tax disputes involving the State Tax Service (DPS) are a classic field for forensic economic examination.

This means the opinion stands on a par with other evidence — testimony, documents, physical evidence. It is neither “above” nor “below” them. The mere fact that the study was carried out by a qualified forensic expert applying specialised knowledge gives the opinion weight, but it does not make it automatically incontestable.

In practice I often explain a simple point to clients: an examination does not “win the case” by itself. It gives the court a reasoned, methodologically tested answer to an economic question — and how that answer is used within the whole body of evidence is for the court to decide.

The principle of free assessment: why the opinion has no predetermined weight

The key rule to remember is the principle of free assessment of evidence. In criminal procedure it is enshrined in Article 94 of the KPK and stated plainly: no item of evidence has predetermined weight. The court assesses each piece of evidence for relevance, admissibility and reliability, and the body of evidence as a whole for sufficiency and interconnection. Rules identical in substance apply in the other types of proceedings: Article 89 of the TsPK, Article 86 of the HPK and Article 90 of the KASU likewise declare that no evidence has predetermined weight for the court.

The practical consequences of this principle are as follows:

• The court is not obliged to base its decision on the opinion simply because it exists.
• The court may prefer other evidence if it is more persuasive.
• Where there are two opinions with opposite results, the court weighs which is more complete, methodologically sound and better aligned with the case materials.
• If the court rejects an opinion, it must give reasons — it cannot simply “disregard” it without explanation.

That is why a good opinion is not one that sounds categorical, but one that transparently shows its source data, methodology and calculation logic. Such an opinion is hard to “shake”, and it is easier for the court to rely on.

What the opinion establishes — and what it cannot contain

This is perhaps the most important point for setting the right expectations. A forensic economic expert establishes facts of an economic nature within the limits of their specialised knowledge. For example:

• whether a particular sum is documented;
• the amount of debt, lost funds or expenses shown by the documents provided;
• whether transactions match the accounting and tax records;
• the financial result of a specific transaction under a defined methodology.

Such questions typically arise in cases that accompany DPS inspections, investigations by the Bureau of Economic Security (BEB), or materials from the State Financial Monitoring Service (Derzhfinmonitoring). But even in these cases the expert stays within economics. What the expert does not decide and has no right to decide:

• A person’s guilt. The question of guilt is exclusively for the court.
• Legal classification. The expert does not establish whether an act is “misappropriation”, “embezzlement” or “evasion” — these are legal assessments.
• Questions of law. Interpreting the provisions of a statute is not the subject of an examination.

If an expert is asked something like “did the person commit a crime” or “are there elements of an offence in the conduct”, a competent expert will refuse to answer or will reframe the question in economic terms. Going beyond one’s competence is one of the most common reasons an opinion later “falls apart” in court.

When the court may reject the opinion

The court assesses the opinion critically and has the right to reject it in whole or in part. In my practice the grounds come down to a few typical groups.

Ground	What it means in practice
Breach of methodology	An improper method was used, or the sequence of the study was broken, making the result unreliable
Exceeding competence	The expert answered legal questions or questions outside their specialty
Incomplete study	Not all documents provided were used; material data were ignored; the scope of questions was narrowed
Contradictions	Internal inconsistencies in the opinion, or conflict with the rest of the case evidence
Doubts about objectivity	Breach of the appointment procedure, signs of interest, violation of the parties’ rights
Insufficient source data	The opinion rests on incomplete or improper documents submitted for study

Methodology deserves separate emphasis. A forensic economic examination is conducted under the Law of Ukraine “On Forensic Expertise” and the Ministry of Justice Instruction on ordering and conducting forensic examinations (Order No. 53/5), applying methods entered in the State Register of Forensic Examination Methods. If an expert departs from a certified methodology without justification, that is a serious ground to doubt the reliability of the result.

Importantly, rejecting an opinion does not always mean the examination was “bad”. Sometimes the problem is that the expert was given an incomplete set of documents, or that the questions were poorly framed. That is why preparing the materials and questions is half the battle; mistakes at that stage prove costly later.

If an opinion raises doubts, the court is not obliged simply to discard it — it may order an additional examination (where the opinion is incomplete or unclear) or a repeat examination (where there are reasonable doubts about its correctness or soundness). A repeat examination is usually entrusted to a different expert. This is provided for by procedural law and happens fairly often in practice.

The role of examining the expert at the hearing

Another tool for testing the opinion is examining the expert at the court hearing. In criminal proceedings this is governed by Article 356 of the KPK; similar mechanisms exist in civil, commercial and administrative procedure, where the expert is called to give oral explanations of their opinion.

The purpose of this questioning is not to “replay” the opinion but to test it: to clarify the methodology applied, verify the source data, remove ambiguities, and gauge how well the expert commands the subject. Both the court and the parties have the right to put questions.

What to watch for during the examination:

• whether the expert explains the methodology consistently and can justify it;
• whether the expert relies on specific documents rather than on assumptions;
• whether the answers stay within the expert’s specialty;
• whether the oral explanations match the written text of the opinion.

A well-prepared expert gets through the questioning calmly, because every figure in the opinion has a documentary basis. If it turns out during questioning that part of the conclusions rests “on the expert’s word”, that is a serious signal for the court.

A court-ordered opinion and a party-commissioned opinion

These are documents of different origin, and the court approaches them with somewhat different “starting” expectations.

An opinion ordered by the court. An examination is ordered by a court ruling (and in criminal proceedings, under the procedure set by the KPK). The expert is warned of criminal liability for a knowingly false opinion, and the procedure is designed to give the parties equal opportunities, so such an opinion is traditionally seen as more “neutral”.

An opinion commissioned by a party. Procedural law allows a party to engage an expert independently and submit the opinion as evidence — a normal and lawful tool. Such an opinion is likewise assessed under the general rules, and the expert bears the same responsibility for its truthfulness, but the other side almost always draws attention to the completeness of the materials provided and the possible one-sidedness of the questions.

The practical takeaway is simple: regardless of who initiated the examination, what is decisive is methodological soundness, completeness of the study and documentary support. A flawlessly prepared commissioned opinion can be more convincing than a superficial court-ordered one — and the reverse is equally true.

A common mistake — treating the opinion as an unconditional “verdict”

The most widespread mistake — made by the parties and sometimes by other participants in the process — is to think that a favourable opinion automatically decides the case. It does not:

• the opinion is assessed together with the rest of the evidence;
• it has no predetermined advantage over other evidence;
• it can be tested through examination of the expert, or an additional or repeat examination;
• it establishes economic facts, not guilt or legal classification.

A realistic view is this: a strong opinion significantly reinforces a position, gives the court a foundation for reasoning its decision, and saves time in a dispute over figures. But it works as part of the evidentiary picture, not in place of it. So a case strategy should be built around the whole body of evidence, using the examination as a precise and reliable instrument within that system.

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If you are preparing a case where the key issue is economic — the amount of damages, the correctness of accounting, the financial result of a transaction — it is worth thinking through the wording of the questions and the completeness of the documents in advance. I would be glad to help with a consultation, or with conducting a forensic economic examination, so that your opinion is not just “one more piece of evidence” but methodologically flawless and able to withstand scrutiny in court.