Scope Discipline Before the First Question Is Asked
The same discipline applies in testimony as in the written work: answer within the scope, state the basis, and decline questions calling for a discipline outside the qualifications on the CV. That boundary is established in the report itself, before any questioning begins, rather than negotiated under cross-examination.
Illinois state courts apply Frye as construed in Donaldson, which reserves the gatekeeping question for new or novel scientific methodology. Records review, forensic inspection, moisture readings and comparison to published standards are none of those, so they generally do not raise a Frye question at all.
Federal matters in the Northern District of Illinois proceed under Daubert, where the court looks more broadly at relevance and reliability. Experience-based testimony is admissible where the expert explains how the experience leads to each opinion and how it applies to the facts, which means tying every opinion explicitly to the licence, the specific facilities record and a recognised standard.
