This question has been addressed in 1 Texas court opinion:
COA09 — January 29, 2026
In a dispute over the validity of a holographic will, the sister of the decedent attempted to disqualify the will through expert handwriting testimony. However, the expert's comparison samples (exemplars) did not consist of the decedent's own signature, but rather signatures the decedent allegedly made on behalf of his parents. The trial court excluded the expert's testimony, and the Ninth Court of Appeals affirmed. The court analyzed the case under Texas Rules of Evidence 703 and 705, concluding that because the expert lacked a 'control' sample of the decedent's actual name and signature, there was an unreliable foundation and an 'analytical gap' that rendered the opinion inadmissible.
Litigation Takeaway
“Expert testimony is only as reliable as the data supporting it; if your handwriting expert relies on representative or third-party signatures rather than authenticated personal signatures, the testimony is likely to be excluded for lack of foundation.”