Test the method behind an expert opinion
For attorneys and technical reviewers examining a proposed expert method.
What would count as evidence that an expert’s method works for the question in this case?
Write down the conclusion, the conditions under which it is supposed to hold and an observable result that would count against it. Then compare those conditions with the tests the expert can actually produce.
Turn the proposed opinion into a testable claim
Ask for the input, procedure and exact output. Estimating a range, classifying an item and identifying one source to the exclusion of others are different tasks. Ask what alternatives the method considered, what reference answer was independently known and what would cause the examiner to give an inconclusive result.
Record the method version, instruments or software, operator training and settings. Ask who selected the comparison material and whether the person scoring the test knew the expected answer. Mark untested conditions, especially ones common in the case but rare in the study.
Read the counts beneath the headline
Obtain counts of correct calls, wrong calls and inconclusive results. Split them by the relevant conditions where feasible. A result reported only on the easy-to-read material can conceal failure on the low-quality inputs that matter most. Ask how inconclusives entered the denominator, how large each group was and whether another examiner could repeat the work.
Finally compare the tested procedure with the procedure used on the disputed item. Request a case-specific work record showing exclusions, deviations and quality checks. A study can support a method in general while leaving a particular application uncertain.
Separate scientific support from the court’s decision
Under Federal Evidence Rule 702, the proponent must show the court that the rule’s conditions are more likely than not satisfied. Those conditions address helpfulness, adequate facts or data, reliable principles and methods, and reliable application to the facts. A validation review informs that analysis. The court decides admissibility under the applicable rules.
Worked example
Illustrative test design. A technician estimates clock drift from video frames. The supporting experiment used uninterrupted, constant-rate recordings. The disputed clip contains gaps. Ask for trials with known timing, comparable gaps and the same software settings. Report the errors and the range tested. If that test is missing, record that limit before relying on an exact timing estimate.
Primary sources
Related work at Agentic Attorney
This expert-method guide is in the shared Agentic Attorney resource collection. The main site describes its work implementing AI for legal teams. Explore Agentic Attorney’s approach to AI implementation.