A common sci-fi movie trope is the image of a “mad scientist” working in the laboratory. Texas appellate lawyers and judges have a similar look when applying Crown Life Ins. Co. v. Casteel, 22 S.W.3d 378 (2000), which deals with the vexing problem of jury charges that mix valid and invalid elements. The Fifth Court’s majority opinion in Kansas City Southern Ry. Co. v. Horton, No. 05-19-00856-CV (March 11, 2021) (mem. op.), after finding one of the plaintiffs’ two liability theories preempted by federal law, found a Casteel issue with a broad-form negligence submission in a personal injury case. It distinguished an earlier Dallas case and a Corpus Christi decision as involving factual-sufficiency rather than legal-validity issues. A dissent took issue with the holding about preemption.