In Gammill v. Jack Williams Chevrolet, Inc. 972 S.W.2d 713 (Tex. 1988) the Court held that all expert testimony must be relevant and reliable under Evidence Rule 702. Gammill, 972 S.W.2d at 726; TEX. R. EVID. 702. This includes the testimony of expert appraisal witnesses in condemnation actions. Appraisal expertise is a form of "specialized knowledge [used to] assist the trier of fact to . . . determine a fact in issue." TEX. R. EVID. 702. It is therefore subject to Gammill's relevance and reliability requirements. Gammill, 972 S.W.2d at 726. Once the Authority made its objection, the burden was on Kraft to establish that Gholson's opinion was reliable. See Gammill, 972 S.W.2d at 718. The Court review the trial court's decision to admit the testimony for an abuse of discretion. See id. at 727.