How Expert Testimony Strengthens the Case Against Dangerous Products

If you’ve been injured by a defective product that has caused serious injury, you have the legal right to hold manufacturers, distributors, or product designers accountable through a product liability lawsuit. But proving that a product was defective (and that it caused your injury) often requires more than just your word or medical records. That’s why we work with expert witnesses to help you with your case.

At Constant Legal Group, we regularly work with highly qualified experts to build strong, evidence-based product liability cases for our clients. What is an expert witness, and why do they matter for your product liability lawsuit?

What Is an Expert Witness?

An expert witness is someone who has specialized knowledge, education, training, or experience in a particular field that is relevant to the case. Unlike a fact witness (such as someone who saw an accident happen), an expert witness offers professional opinions that help the court or jury understand complex issues.

In a product liability case, expert witnesses may be called to answer questions like:

Was the product designed or manufactured incorrectly?
Did the product fail in a way that a consumer could not have anticipated?
Were the instructions or warnings adequate and consistent with industry standards?
Did the defect cause or contribute to the plaintiff’s injuries?

Their role is not to advocate for either side, but to provide objective, qualified opinions based on their expertise.

What Expert Witnesses Can—and Cannot—Do

Expert witnesses are a great asset in product liability and mass tort litigation, but their roles do have some clear boundaries. In general, they are there to:

Analyze the product design or manufacturing process
Reconstruct the accident or failure
Provide scientific or technical explanations to support causation
Evaluate compliance with safety regulations or industry standards
Estimate damages or future costs (e.g., through vocational or economic experts)
Offer clear, credible testimony that helps the jury understand complex issues

While they can help your case, their testimony is not a catch-all when it comes to providing everything you need to win your case. Some of the things they cannot do include:

Offering opinions outside their area of expertise
Making legal conclusions (e.g., “this company is liable” or “this violates the law”)
Testifying based on speculation or unverified assumptions
Acting as an advocate rather than an objective source of insight

Courts carefully vet expert witnesses to ensure their testimony is based on reliable methods and valid reasoning, not bias or guesswork.

What Types of Experts Are Used in Product Liability Cases?

Because product liability cases often involve technical, medical, and scientific issues, several types of experts may be needed to build a strong case:

Engineering Experts

These experts evaluate the design, materials, functionality, and safety of the product. They can identify design flaws, structural weaknesses, or manufacturing deviations.

Example: In a case involving a defective ladder that collapsed, an engineer could determine whether the design failed under normal use conditions.

Human Factors or Warnings Experts

These experts specialize in product labeling, usability, and instructions. They assess whether the warnings were adequate and if the product was reasonably safe for average consumers.

Example: In a case involving a consumer appliance, a human factors expert might show how the lack of clear instructions contributed to a user’s injury.

Materials Scientists or Chemists

These professionals evaluate whether the product was made with safe, durable, and appropriate materials.

Example: In a lawsuit over a medical implant that degraded inside the body, a materials scientist could examine whether the materials used were biocompatible and stable.

Medical Experts

Doctors or specialists may be needed to connect the defective product to your injury and assess the long-term impact. They can explain how the injury occurred, what it means for your future, and what care you may need.

Economic or Vocational Experts

These professionals help calculate the financial impact of an injury, including lost wages, reduced earning capacity, and the cost of future medical care.

How Expert Witnesses Are Used in Product Liability Cases

They Prove Causation

One of the most difficult elements to prove in a product liability case is causation, that the product defect directly caused the injury. Expert witnesses are essential for drawing that connection in a scientifically valid way.

They Strengthen Credibility

Jurors may be unfamiliar with technical concepts or medical jargon. Expert witnesses help bridge the gap between complicated science and plain language, making your case more relatable and persuasive.

They Can Overcome Defense Tactics

Manufacturers often argue that a product was misused or that the plaintiff’s injuries were caused by something else. Expert testimony can dismantle those defenses by offering clear, fact-based explanations.

They Set the Standard

Experts are often the ones who define the industry’s safety standards. When an expert explains how a product violated those standards, it can powerfully illustrate the manufacturer’s negligence.

We Leverage Expert Testimony to Help You

At Constant Legal Group, we understand that complex cases require deep expertise. That’s why we’ve built relationships with respected experts across disciplines.

When we take on a product liability case, we:

Identify the right experts early to evaluate the product, injury, and legal viability
Work closely with those experts to prepare detailed reports and courtroom presentations
Use expert findings to pressure manufacturers into fair settlements—or to present strong cases in trial

What Should You Do If You Think a Product Caused Your Injury?

If you believe a defective product caused you or a loved one serious harm:

Preserve the product – Do not throw it away or alter it in any way.
Seek medical attention – Get treatment and document your injuries.
Collect all records – Save instructions, packaging, receipts, and any warranty documents.
Avoid speaking to the manufacturer or insurer – They may try to limit your claim.
Call our product liability lawyers – The sooner you speak us, the sooner our experts can begin reviewing your case.