A manufacturing defect exists when a product differs from its intended design and that deviation makes it unreasonably dangerous. Courts generally focus on whether:

1. The product departed from design specifications
2. The deviation occurred during manufacturing or assembly
3. The defect existed when the product left the manufacturer’s control
4. The defect caused injury during normal or foreseeable use

Unlike design defect cases, manufacturing defect claims often rely on physical evidence, inspection records, and comparison to non-defective units.

Manufacturing defect claims usually stem from problems that arise during production, assembly, or quality control. Common causes include:

• Errors in assembly or installation
• Use of defective or substandard materials
• Contamination during manufacturing
• Equipment malfunctions on the production line
• Failure to follow design specifications
• Inadequate quality control or inspection procedures
• Improper packaging or handling before distribution

Because these issues occur after the design phase, the defect is often unintentional but still dangerous.

Manufacturing defects can occur across nearly every product category. The following examples involve products that became unsafe due to production-level errors, not flawed designs.

A manufacturing defect becomes a legal matter when:

• A person is injured by a product that deviates from its intended design
• The injury can be traced to a production or assembly error
• The product was being used as intended or foreseeably misused

Because the design itself may be safe, liability often turns on proof of deviation, not risk–benefit analysis.

Manufacturing defect claims may involve multiple responsible parties depending on where the error occurred in the production or distribution chain.

Potentially liable parties include:

Manufacturers are commonly liable when defects arise from assembly errors, defective materials, or inadequate quality control.

Suppliers may be liable if a defective component caused the finished product to become unsafe.

Third-party manufacturers may be responsible when defects arise during outsourced production.

In some jurisdictions, distributors or retailers may be liable for placing a defectively manufactured product into the marketplace.

Companies selling products under their brand may be treated as manufacturers for liability purposes.

Several factors often influence the strength and value of a manufacturing defect claim, including:

• Clear evidence of deviation from design specifications
• Preservation of the defective product
• Quality control and inspection records
• Scope of the defect (single unit vs. batch)
• Severity and permanence of injuries
• Jurisdiction-specific liability rules

Manufacturing defect cases are often more straightforward than design defect claims, but still require technical proof.

Manufacturing defects are one category of product defects. Depending on how an injury occurred, a claim may fall under a different or overlapping category.

• Design Defects: A claim may involve a design defect when the product is dangerous due to its blueprint, even if manufactured correctly.

• Failure to Warn: Some injuries result from inadequate warnings or instructions rather than a flaw in manufacturing.

These categories are often evaluated together when determining how a product liability claim should be structured.

Design defect claims fall within product liability law, but they often intersect with other recognized areas of law that govern responsibility, remedies, and procedural posture in injury cases.

• Personal Injury Law: Most manufacturing defect claims seek compensation for physical injuries, medical costs, and lost income.

• Wrongful Death Law: Fatal injuries caused by defective products may give rise to wrongful death claims.

• Consumer Protection Law: In some cases, manufacturing defects may intersect with consumer protection statutes, particularly when unsafe products are sold or distributed.

Manufacturing defect claims focus on what went wrong during production, not whether the product was poorly designed. When a product deviates from its intended design and causes injury, manufacturers and others in the supply chain may be held responsible.

Understanding manufacturing defects helps clarify how product liability law addresses injuries caused by preventable production errors.