Dueling Hog Poo Odor Expert Witnesses: One In, One Out

What constitutes an “offensive odor” is subjective opinion, reasonably excluded, the US Fifth circuit has held, while also agreeing with the district court that an adverse expert's opinion offering a “proxy” for such offensive odors, the presence hog feces, was admissible.

The result is that a small group of neighbors in rural North Carolina have won their case against the world's largest hog producer, although the appellate court left open a reduction in their $3.25 million jury award.

This is the first appeal in a series of five verdicts against Murphy-Brown, a subsidiary of Smithfield Foods, cases in which some 36 plaintiffs have won almost $550 million in similar suits, although those awards were later reduced by the court to $98 million due to limitations on punitive damages under state law.

In McKiver et al. v. Murphy-Brown, McKiver and his neighbors had initially filed suit against Kinlaw Farms under a state nuisance law for the “odors, pests, and noises” coming from the farm.

Under contract with Murphy-Brown, Kinlaw operated an industrial-scale hog feeding farm with an average 15,000 hogs generating an estimated 153,000 pounds of feces and urine daily, which was pumped into lagoons and then sprayed on the adjacent fields.

After McKiver learned of Murphy-Brown's strict control over Kinlaw Farms' operations, it dismissed its state actions and refiled suit in federal court solely against Murphy-Brown.

While McKiver's nuisance suit included reference to dumpsters of dead hogs attracting buzzards and flies, and 24-hour trucking operations, the central complaint involved the odor of hog feces.

Murphy-Brown retained Dr. Pamela Dalton, Ph.D, MPH, whose doctorate is in Experimental Psychology and specializes in “how cognitive and emotional processes modify the way we perceive odor and sensory irritation from volatile chemicals.”

To support her conclusion, Dr. Dalton conducted a study using six monitors trained on odor observation techniques, including the use of a field olfactometer known as the Nasal Ranger,¹ which allows the air nearby to be sniffed at varying dilutions with clean air. Over the course of the study, the monitors only once found a dilution level above 7:1. Dr. Dalton's expert opinion was that “unless an odor can be detected at a 7:1 dilution or higher, it is not an objectionable odor.”

The district court allowed Dr. Dalton to testify about the “unreliability of human self-reports of odor”, but it excluded her testimony about her “odor monitoring study and her opinion regarding the lack of odor nuisance emanating from Kinlaw Farm[s],” finding that “North Carolina (unlike some other jurisdictions) has not adopted a dilution to threshold ratio or any other objective standard for assessing whether an odor is objectionable.” The court noted that even Dr. Dalton recognized that “the perception of odors is a highly subjective experience.”

McKiver retained Dr. Shane Rogers, an Associate Professor of Civil & Environmental Engineering at Clarkson University, whose specialty was described as “the fate and transport of fecal pathogens.” Dr. Rogers took air, manure, and lagoon samples at Kinlaw Farms, and also took samples from the neighbors' properties, including the exteriors of their homes for the presence of a DNA indicator known as pig2bac to show the presence of fecal material.

Although he was retained to support McKiver's claim that the hog odors were sufficiently offensive to be a legal tort of nuisance, Dr. Rogers was careful that he never claimed to be an expert on the ability of humans to perceive odor. He only testified that the evidence of pig2bac was a reliable proxy for evidence of odor, that “pig feces has to be in relatively high concentrations to facilitate … detection” and that “a detectable presence of pig2bac indicated the presence of comparatively higher levels of pig feces and resulting odor.”

The dissenting appellate court opinion found that the district court abused its power in allowing Dr. Roger's opinion, in particular his use of pig2bac in a manner that had not been peer-reviewed, but the majority were unwilling to go that far.

The concurring opinion written by Judge J. Harvie Wilkinson III, the court's former chief judge, suggests he had little appetite for overturning the district court. While Judge Wilkinson said he was “… not so naive as to imagine that hog farming could ever be an antiseptic enterprise,” he had little patience with Murphy-Brown and the “outrageous conditions at Kinlaw Farms,” writing:

“If this were my property, I would be outraged at some of these conditions …. And less fortunate fellow citizens, they have property rights too … They have a right to good health, and they have a right to enjoyment of their property.”

The tort of nuisance has a long history in English Common Law, going back to Henry II in 1166 and the assize of novel disseisin,² with many cases involving pigsties, and more often than not with the powerful landowner winning against those with “delicate noses.” Progress has been made.