Component Parts Doctrine

A legal principle that limits the liability of a company that made a non-defective part when injury was caused by the larger finished product into which the part was incorporated by someone else. In asbestos cases, defendants often invoke it to argue they should not be responsible for harm caused by asbestos-containing materials added to their product by a third party, or for asbestos parts later attached to their equipment.

Origin

The doctrine grew out of 20th-century American product liability common law and was formally articulated in the Restatement (Third) of Torts: Products Liability § 5 (1998). California's decision in O'Neil v. Crane Co. (2012) became a leading asbestos-specific application, limiting a pump and valve maker's duty to warn about asbestos gaskets and insulation added by the Navy.

Significance in Asbestos Context

This doctrine is one of the most common defenses raised by equipment manufacturers (makers of pumps, valves, turbines, boilers, and brakes) whose products were originally sold without asbestos but were routinely used with asbestos gaskets, packing, insulation, or friction materials supplied by others. If the defense succeeds, the equipment maker may avoid liability even though the worker was exposed while servicing their machine. Outcomes vary sharply by state: some jurisdictions (like California in O'Neil) apply the doctrine broadly, while others (such as Washington in Macias v. Saberhagen and Maryland in May v. Air & Liquid Systems) impose a duty to warn when the manufacturer knew or should have known its product would be used with asbestos. Which state's law governs your case can therefore significantly affect which defendants remain on the verdict form.

Example Sentence

The valve manufacturer moved for summary judgment under the Component Parts Doctrine, arguing it had no duty to warn about the replacement asbestos packing the shipyard later installed in its valves.

Related Terms

Bare Metal Defense, Duty to Warn, Strict Liability, Failure to Warn, Sophisticated User Doctrine, Foreseeability

Notes

• Ask your legal team which state's law will govern your case. The Component Parts and Bare Metal defenses succeed in some states (notably California) and fail in others (notably Washington, Maryland, and under maritime law per Air & Liquid Systems v. DeVries, 2019).
• Preserve any evidence showing the original equipment was sold with asbestos parts (original gaskets, factory insulation, OEM manuals specifying asbestos packing). This can defeat the defense by showing the asbestos was part of the manufacturer's own product.
• Save service records, parts catalogs, and military or employer specifications that show the manufacturer knew asbestos replacement parts would be required to keep their equipment running.
• This defense most often arises in cases involving Navy veterans, power plant workers, refinery workers, and mechanics who serviced industrial equipment rather than installed raw asbestos products.