Expert Testimony in Texas Courts:
Separating the Wheat from the Chaff

by Brent Miles

Expert testimony is an essential aspect of the legal system. Expert witnesses provide specialized knowledge and insights into technical matters that the average person might not possess. In Texas, expert testimony has been a point of contention in civil cases for several decades. This article will discuss the recent case of Helena Chemical Company v. Cox and its implications for expert testimony in Texas state courts.

Helena Chemical Company v. Cox
In March 2023, the Texas Supreme Court issued its opinion in the case of Helena Chemical Company v. Cox. The case involved a dispute between Plaintiff and Helena Chemical Company over damage to Plaintiffs’ cotton crop caused by the herbicide Sendero. Specifically, Plaintiffs claimed that while Helena was supervising an aerial application of their herbicide onto various parcels of the nearby Spade Ranch, the herbicide drifted onto Plaintiffs’ farms and damaged their cotton crops.

The district court held an extensive hearing on the motion to strike the expert testimony. Plaintiffs’ experts included: (1) a former inspector with the TDA who opined that Helena breached the standard of care for use of aerial herbicides, that weather conditions and faulty application techniques caused excessive drift, and that the Spade Ranch application of Sendero damaged 15,000 acres of cotton as claimed by the plaintiffs; (2) an agronomist and entomologist who opined that damage from Sendero occurred in all the plaintiffs’ fields, basing this opinion on the Sendero label, plant tissue samples that were tested for the cotton-harming ingredients of Sendero, observations from the farmers, and the report of the TDA inspector who investigated the incident; (3) a crop-dusting pilot who opined that it was highly probable that Helena's application of Sendero had caused the herbicide to drift onto the plaintiffs’ fields because of wind and temperature conditions at the time, relying on a “rule of thumb” that as much as 50% of aerially applied pesticide drifted away from the Spade Ranch fields onto Plaintiff’s fields; (4) an environmental chemist who has studied the effect of Sendero on crops opined that Sendero results in long-term damage to cotton fields, and based on the TDA inspector’s report, concluded that Sendero drifted onto the plaintiffs’ farms and damaged their cotton crops; and (5) a farmer who had no prior experience evaluating herbicide exposure and no experience with Sendero. None of Plaintiff’s experts visited the affected fields, nor did any of the experts collect cotton samples.

Predictably, the district court granted the motion to strike and summary judgment for Helena, but the court of appeals reversed, reasoning that although Plaintiffs’ experts could not specifically trace the purported drift of the herbicide from the Spade Ranch to Plaintiffs’ cotton fields. They provided a reliable scientific basis for their opinions, that Plaintiffs’ cotton crops were damaged by a large-scale aerial application of the herbicide to Plaintiffs’ fields. The appellate court recognized that Plaintiffs’ experts only relied on a report from an inspector with the Texas Department of Agriculture which said the Spade Ranch’s application of Sendero was a possible cause of Plaintiff’s crop damage, along with observations that Helena's aerial application of Sendero was the only such large-scale application at the relevant time and place. Accordingly, the appellate court saw no analytical gap in Plaintiff’s experts reaching their various conclusions even with these limited information sources.

On appeal to the Supreme Court of Texas, the central question was whether the plaintiffs’ experts offered reliable evidence of causation. The Texas Rules of Evidence states that a witness may be qualified to testify as an expert based on his knowledge, skill, experience, training, or education. Although an expert witness need not always be formally credentialed as a scientist, expert testimony on scientific matters—such as the aerial drift of herbicide particles or the effect of herbicide exposure on plants— naturally must be grounded in the methods and procedures of science. The Supreme Court also has recognized that expert testimony is unreliable if the gap between the data and the opinion proffered is simply too attenuated. Here, Plaintiffs argued that apart from the expert testimony offered from their experts, the lay opinions of the farmers themselves about the source of their crop failure can provide evidence of causation sufficient to survive summary judgment. However, the Supreme Court disagreed, holding that expert testimony is required when an issue involves matters beyond jurors’ common understanding.

In relation to proving causation of whether plaintiffs’ crops were exposed to Helena’s Sendero, the Court offers multiple ways in which Plaintiff could have used their experts to prove this up. The Court recognized that one obvious way to show toxic contamination over a widespread area in such a case would be laboratory test results from spots throughout the allegedly affected area, coupled with reliable evidence that the tested areas are representative of the whole area for which damage is claimed. The Court went on to offer that plaintiffs could have proffered a recognized model of the herbicide’s drift through the air onto the allegedly affected properties. Such evidence could provide a reliable indication that Helena’s product actually reached the allegedly damaged areas.
The Plaintiffs’ experts did not attempt to do this. Rather, they acknowledged that scientific models of aerial drift exist, but they did not employ these models or make any effort to recreate the aerial drift that would have occurred from the Spade Ranch given the weather conditions on the alleged dates of crop damage. The court concluded that Plaintiff’s experts essentially expressed the view that aerial drift must have occurred here because of the widespread damage alleged—even though the damage pattern was not consistent with typical drift patterns. The Court found that Plaintiffs’ expert conclusions lacked a reliable foundation grounded in science and amounted to no more than speculation. As such, the Supreme Court agreed with the district court and reinstated summary judgement for Helena Chemical Company.

The Court's ruling on the admissibility of expert testimony highlights the importance of reliable and well-supported expert opinions in toxic tort cases.