Who Qualifies as an Expert

Parties assemble credentials as though the question were a competition, and the actual test is narrower and more practical. Does this person know something about this particular question that the decision-maker does not, and did they acquire that knowledge in a way that makes it reliable.

The five routes to qualification

Knowledge. Substantive familiarity with a subject, however acquired, which covers the person who has read and absorbed a field without ever having been examined in it or employed within it.

Skill. Practical ability demonstrated by doing the thing, which is the route for trades, crafts and technical work where competence is shown by output rather than by certificates.

Experience. Years spent working in a field, which qualifies people with no formal training at all and is frequently the strongest route where the question is about ordinary practice.

Training. Instruction short of a formal qualification, including manufacturer courses, professional development and instruction received within an organization.

Education. Formal study and the qualifications that follow, which is the route people imagine is the only one and is in fact merely the most visible.

Any one is enough. The routes are alternatives rather than requirements, so a person qualified by twenty years of experience needs no certificate, and the absence of one is not a deficiency.

Matching the qualification to the question

Expertise is specific. A qualification in a broad field does not make somebody an expert in every corner of it, and the enquiry is always about the particular question being asked.

The commonest successful challenge. Not that a witness lacks credentials, but that their credentials are in an adjacent area rather than in the one their opinion concerns.

Recency matters in changing fields. Somebody whose practical experience ended twenty years ago may be describing a field that no longer works the way they remember it.

Practical and academic differ. A researcher and a practitioner in the same field frequently answer different questions well, and which one is needed depends on what is actually in issue.

Say what the qualification is for. Framing the expertise as relating to a specific question, rather than to a field in general, forestalls the challenge that would otherwise be made, and it also tells the reader immediately what the report is and is not offering.

The report itself carries the fit. A properly constructed report states the question, the expertise engaged by it and the connection between them, which is dealt with in what an expert report must contain.

Whether the field itself exists

A prior question. Before anybody's qualification matters, there has to be a body of specialized knowledge to be qualified in, and some claimed fields do not survive that examination.

Testability and error rates. Whether the technique can be tested, whether it has a known rate of error, and whether it has been subjected to scrutiny by others working in the area.

General acceptance. Whether people working in the relevant community regard the method as sound, which remains the test in some jurisdictions and a factor in others.

Experience-based fields are not exempt. Where a field rests on experience rather than measurement, the question becomes whether that experience reliably produces the conclusions claimed for it.

Some long-established fields have been questioned. Several techniques with decades of courtroom use have been re-examined and narrowed, which is discussed in handwriting and the people who examine it.

Establishing qualification in practice

A curriculum vitae is the starting point. Setting out education, employment, publications and previous instructions, and it should be accurate to the letter because every line of it is checkable.

Experience needs describing, not listing. Twenty years in a role means little without an account of what the work actually involved and how often the specific question arose within it.

Previous evidence is relevant. How often the witness has given evidence, for which side, and whether any court has commented on their evidence, all of which is discoverable.

Membership is weak on its own. Belonging to a professional body demonstrates that somebody paid a subscription, and it becomes meaningful only where admission required demonstrated competence.

Be precise about what is claimed. Overstating a qualification, even slightly, gives an opponent a legitimate attack on credibility that has nothing to do with the substance of the opinion.

Challenging qualification

Attack the fit, not the person. The productive challenge is that the expertise does not reach this question, which is a narrow point that decision-makers understand immediately.

Check every claim. Publications, positions and qualifications are all verifiable, and a discrepancy in a curriculum vitae damages an opinion far more than any disagreement with its content.

Ask about the proportion of work. A witness who gives evidence almost exclusively for one side, or who spends most of their time on litigation rather than practice, invites a question about independence.

Consider whether to challenge at all. An unsuccessful attack on qualification strengthens the witness, and it is frequently better to accept the expertise and attack the basis, per the basis of an opinion.

Raise it early. Qualification challenges made in advance are decided on their merits, while those raised at a hearing look tactical and are treated accordingly.

Qualification is a threshold rather than a contest. The question is whether this witness knows something useful that the decision-maker does not, and once that is answered the argument moves to the opinion itself.

The breadth of the routes surprises people who expect credentials. Experience alone qualifies, skill alone qualifies, and a person with no formal education in a subject may be the best available witness about how it works in practice.

The narrowness of the fit surprises them equally. A qualification in a broad field is not a qualification in every part of it, and the most successful challenges are about adjacency rather than about competence.

Underneath all of it sits the question whether the field exists at all, which is asked more often now than it once was. Several techniques with long courtroom histories have been re-examined and confined to narrower claims.

For anybody instructing an expert, the practical advice is to be precise and modest. State the specific question, describe the experience that bears on it, check every line of the curriculum vitae, and claim nothing that cannot be evidenced.