By Noah Bolmer

Three cases from the 1960s offer a surprisingly modern look at expert testimony. In disputes involving medicine, damages, and professional judgment, the experts’ work became an important part of how the courts understood the issues before them. Each case turns on a different aspect of expert practice, from the assumptions underlying an opinion to the evidence supporting a professional judgment. The details may be decades old, but the questions they raise will be familiar to experts working today.

1. A Broken Leg and a Question of Expertise

In Darling v. Charleston Community Memorial Hospital (1965), 18-year-old Dorrence Kenneth Darling II broke his leg playing football and was taken to Charleston Community Memorial Hospital in Illinois. Dr. John Alexander treated the fracture with traction and a plaster cast, but the leg became severely swollen and the toes turned dark, cold, and insensitive. His condition deteriorated despite further treatment, and he was eventually transferred to Barnes Hospital in St. Louis, where doctors attempted to save the leg before amputating it below the knee. Darling and his family sued the initial hospital, alleging negligent treatment. 

The jury returned a $150,000 verdict, later reduced to $110,000 to account for Alexander’s settlement. The appellate court affirmed, and the Illinois Supreme Court granted review. Among the issues was the scope of cross-examination of the hospital’s medical experts, including whether counsel could question them about recognized medical authorities even when those authorities had not been relied upon in forming their opinions. 

The Expert: Know the Field 

The hospital argued that the experts should not have been questioned about medical authorities they had not relied upon in forming their opinions. The Illinois Supreme Court rejected that position and held that the prior rule was “unsound.” Cross-examination could include the views of recognized authorities expressed in professional treatises and periodicals, provided the authority of the source was established. 

“An individual becomes an expert by studying and absorbing a body of knowledge,” the court wrote. To prevent questioning about that body of knowledge, it continued, would “protect the ignorant or unscrupulous expert witness.” The court therefore permitted counsel to test an expert’s testimony against “the views of recognized authorities, expressed in treatises or periodicals written for professional colleagues.” 

The Lesson: Authority Beyond the Report 

The sources cited in an expert’s report are only part of the professional landscape surrounding an opinion. If a recognized authority bears directly on the disputed proposition, the expert should know where that authority stands and be able to explain any meaningful disagreement. While the expert report identifies the authorities that support an opinion, those citations do not necessarily encompass the broad body of knowledge upon which the opinion rests. 

That does not require an expert to master every publication in a field. It does, however, require familiarity with the principal authorities surrounding the issue and in particular, any significant disagreements among them. An expert who knows only the material cited in the report may be well-prepared to explain the opinion itself but vulnerable when opposing counsel asks about surrounding literature. Darling draws a useful line between materials which support an opinion and knowing the field in which that opinion must survive. 

2. When the Numbers Look More Certain Than They Are

In Herman Schwabe, Inc. v. United Shoe Machinery Corp. (1962), Schwabe was a manufacturer of shoe machinery competing with United Shoe Machinery, which dominated the shoe-machinery market. The federal government had previously sued United for unlawful monopolization, and that case resulted in a decree requiring changes to United’s practices. Schwabe then brought its own lawsuit, claiming that United’s unlawful conduct had cost Schwabe sales and profits during the years before those changes took effect. The problem was figuring out how much business Schwabe would have had if United had not engaged in the unlawful conduct. 

Schwabe hired economist Peter Max to answer that question. Max constructed a model of the business Schwabe supposedly would have done in the shoe-machinery market. He started with Schwabe’s share of the market for one type of machine outside the shoe industry, assumed that the same share could be applied to United’s shoe-machinery business, extended that assumption across 24 types of machinery, and then estimated the profits Schwabe would have earned from those sales. His calculation produced more than $2.5 million in claimed damages, presented through tables, charts, and graphs. The district court excluded the evidence, and the Second Circuit affirmed. 

The Expert: Assumption after Assumption 

The court examined the assumptions underlying Max’s calculation and found problems at several points. The record did not establish his estimate of the size of the non-shoe market. The evidence also did not establish that Schwabe’s share of that market could be used to predict its share of United’s shoe-machinery business. Max then applied that percentage across different types of machinery, including machinery in which Schwabe had not previously competed. 

The court also rejected Max’s choice of Schwabe’s 1946 profit margin for calculating damages for the later damages period. That margin was the company’s highest and was far above its average during the years for which damages were claimed. Judge Friendly described the resulting exhibits as “an array of figures conveying a delusive impression of exactness” and concluded that the leap from the data to the damages figure was too great for a jury to make. 

The Lesson: Test the Dependency Chain 

An expert opinion can become increasingly elaborate while resting on a premise that was never adequately established. An expert should examine each material assumption in the analysis and consider what conclusions depend on it. The more consequential the assumption, the more important it is to establish why the evidence supports it before building further analysis on top of it. 

Schwabe illustrates the problem clearly. Max’s calculation moved from a market estimate to a market share, from market share to projected sales, and from projected sales to projected profits. Each conclusion supplied the foundation for the next. The same structure can appear in any expert analysis. When an important conclusion depends on an earlier judgment, the expert should be prepared to defend that earlier judgment on its own terms, rather than relying on the later conclusion to make the chain appear stronger than the foundation warrants.  

3. The 12-Foot Problem

In Stevens Concrete Pipe & Products, Inc. v. Burgess (1968), East Baton Rouge Parish adopted a specification requiring certain concrete drainage pipe to be at least 12-feet-long. Stevens Concrete Pipe produced 8-foot pipe and challenged the requirement, which effectively prevented it from competing without a costly plant conversion. The parish defended the specification on engineering grounds, arguing that longer pipe meant fewer joints and better hydraulic performance. 

The dispute centered on whether that claimed advantage was substantial enough to justify excluding the shorter pipe. Stevens’s experts examined laboratory data from the St. Anthony Falls Hydraulic Laboratory and concluded that the difference in the relevant friction factor between 8-foot and 12-foot pipe was minimal; only 2/100,000. The district court found that the parish’s engineers could not identify scientific data, technical literature, experience, or other factual support for the magnitude of the advantage they claimed. The Louisiana Supreme Court agreed that the 8-foot pipe was substantially equal in utility to the specified 12-foot pipe and affirmed under Louisiana’s closed-specification law. 

The Expert: When Experience Isn’t Enough 

The parish’s engineers were qualified professionals, and their underlying intuition was not unreasonable. Fewer joints could plausibly affect the pipe’s performance. What was missing was support for the degree of effect they attributed to that difference. Stevens’s experts were able to move the question from professional expectation to something that could be tested empirically. 

The Supreme Court specifically noted that the plaintiff’s expert testimony was supported by the scientific data introduced at trial. That support gave the court something concrete against which to evaluate the parish engineers’ judgment. The competing opinions could be assessed against the underlying evidence, including testing that measured the effect at issue. The court concluded that the evidence did not support the magnitude of the hydraulic advantage the parish claimed. 

The Lesson: Don’t Confuse Judgment with Evidence 

Professional judgment is part of expert analysis, but it does not become evidence simply because it comes from an experienced professional. An expert can reasonably begin with an expectation drawn from experience, but when the conclusion depends on the size or significance of an effect, the expert should be able to identify evidence supporting that particular judgment. In Stevens Concrete Pipe, the proposition that fewer joints could improve performance was plausible; the claim that the improvement was large enough to justify the specification was something else. The testing showed that the effect was negligible. The lesson extends well beyond engineering: when an expert’s judgment is carrying the weight of an opinion, the expert should know whether the evidence can keep the conclusion from springing a leak. 

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