Proving Causation with Experts: From Engineering to Epidemiology

When a dangerous or defective product causes harm, proving it in court takes more than simply showing an injury occurred. The injured person must also establish causation—that the product defect directly caused the harm. This step is often the most fiercely contested in product liability cases, and it usually requires the testimony of highly qualified experts.

At GetCompensation.law, we understand that building a strong causation chain is critical to winning against manufacturers and their insurers. These companies are well-prepared, backed by teams of attorneys who routinely challenge the credibility of experts and the reliability of their methods. To succeed, victims need skilled lawyers who know how to select, prepare, and present experts capable of translating science into courtroom evidence.

The Role of Causation in Product Liability

Product liability cases generally hinge on three elements:

1. The product was defective or unreasonably dangerous.
2. The defect existed when it left the manufacturer.
3. The defect directly caused the injury.

While the first two elements may be demonstrated with documents, design records, or recalls, causation is where cases most often rise or fall. It is not enough to show that a product was defective and that the plaintiff was harmed. Plaintiffs must connect the dots, proving that the specific defect caused the injury in question.

For example, if a consumer develops cancer after long-term exposure to a chemical in a household product, experts must demonstrate both that the chemical is capable of causing cancer (general causation) and that it actually caused cancer in this individual (specific causation). Without that link, defendants will argue the illness could have resulted from other factors.

Daubert vs. Frye Standards

Before expert testimony can even be heard by a jury, it must first pass judicial scrutiny. Courts apply either the Daubert or Frye standard to determine whether the expert’s opinions are admissible.

• The Frye Standard (used in some states): Focuses on whether the expert’s methodology is “generally accepted” within the relevant scientific community.
• The Daubert Standard (used in federal courts and most states): More rigorous, requiring judges to act as “gatekeepers.” Courts evaluate whether the testimony is based on reliable principles and methods, whether it can be tested, whether it has been peer-reviewed, and the known error rates.

The difference can be decisive. Under Frye, consensus in the scientific community may be enough. Under Daubert, courts dig deeper, examining the expert’s reasoning and methodology. A strong lawyer knows which standard applies and prepares experts accordingly.

Types of Experts in Product Liability Cases

Product liability cases span industries and scientific disciplines, meaning no single type of expert can cover every aspect of causation. Instead, attorneys build multidisciplinary teams of specialists, each addressing a different piece of the puzzle.

• Engineering Experts
  These professionals examine how the product was designed, manufactured, and tested. An engineer might testify that a medical device had a structural flaw or that a car part failed under normal conditions.
• Medical Experts
  Physicians, toxicologists, and pharmacologists provide evidence linking the defect to physical injury. For instance, they may show how a drug’s active ingredient causes harmful side effects.
• Epidemiologists
  Epidemiologists study patterns across populations. In toxic exposure cases, they analyze whether individuals exposed to a chemical have higher rates of disease than those who were not. Their testimony is especially important in proving general causation.
• Industry Experts
  Sometimes the key lies in industry standards and compliance. Experts with knowledge of regulatory rules, manufacturing protocols, or safety standards can show that the manufacturer cut corners or failed to follow best practices.

When combined, these experts create a credible causation chain—a step-by-step demonstration of how the defect occurred and why it led to the plaintiff’s injury.

Selecting the Right Expert

Not every expert makes a good witness. Even brilliant scientists can be ineffective in court if they cannot communicate clearly. Successful attorneys know how to balance academic credentials, courtroom presence, and credibility.

Key considerations include:

• Credentials and Experience: Jurors are more likely to trust experts with established reputations, peer-reviewed publications, or industry leadership roles.
• Prior Testimony: Defense counsel often digs into whether the expert has been excluded in prior cases. A track record of admissibility strengthens credibility.
• Communication Skills: Experts must translate complex science into terms understandable to judges and jurors without appearing condescending.
• Neutrality: A witness who appears biased or overly invested in the outcome can lose credibility. The most effective experts are authoritative yet balanced.

By carefully vetting experts, attorneys reduce the chances that testimony will be excluded under Daubert or undermined during cross-examination.

Building a Credible Causation Chain

A strong causation case is not built on one expert alone. It requires weaving together different strands of scientific evidence into a cohesive narrative.

• Engineering Data: Proves how the product failed.
• Medical Testimony: Links the failure to the injury mechanism.
• Epidemiological Evidence: Establishes that exposure is capable of causing harm in humans.
• Case-Specific Analysis: Connects the plaintiff’s unique circumstances to the injury.

For example, in a case involving a defective hip implant, an engineer may testify that the device’s metal-on-metal design generated harmful debris. A toxicologist may explain how the debris leads to tissue damage. A surgeon may then testify about how this specific patient’s implant caused complications. Together, these perspectives leave little room for the defense to argue alternative causes.

Challenges and Defense Strategies

Defense teams are highly skilled at attacking causation. Common strategies include:

• Pointing to Alternative Causes: Suggesting that genetics, lifestyle, or unrelated medical conditions explain the injury.
• Discrediting Experts: Highlighting inconsistencies, questioning methodology, or portraying them as “hired guns.”
• Undermining Epidemiology: Arguing that population-level data does not prove causation in an individual case.

Plaintiff attorneys must anticipate these tactics. Skilled lawyers prepare their experts through mock cross-examinations, reinforce testimony with multiple lines of evidence, and create a clear record for appeal.

Why Experienced Lawyers Matter

Expert testimony can make or break a product liability case. Insurers and manufacturers know this and often settle cases quietly when faced with a well-prepared expert team. Conversely, plaintiffs without strong experts may see their claims dismissed before reaching a jury.

This is why working with top trial attorneys is critical. At GetCompensation.law, we connect injured victims with lawyers who have the resources and experience to bring in the best experts nationwide. These attorneys know how to withstand defense challenges, meet Daubert or Frye standards, and present compelling evidence to juries.

When the stakes are high, you need advocates who aren’t afraid to go to war with the insurance companies—backed by science and expertise that jurors can trust.

Conclusion

Proving causation in a product liability case is rarely straightforward. It requires the combined efforts of engineers, physicians, epidemiologists, and industry specialists, all coordinated by experienced attorneys who understand the science and the law.

The difference between winning and losing often comes down to the strength of the experts and the clarity of the causation chain they establish. If you or a loved one has been harmed by a defective product, don’t face the challenge alone. Seek out lawyers who can build the team you need—and hold manufacturers accountable.

At GetCompensation.law, we’ll help you determine how much the insurance company really owes you and ensure you have experts ready to prove it.