March 23, 1998 Design News
Latest advice on engineering and the law
When is a product defective?
Phillip M. Davis Davis, White & Pettingell, LLC, Boston
A simple, uniform legal definition of a defective product
is impossible across the 50 different state judicial
districts and eleven federal districts that comprise
Since we must deal with slightly different definitions
of design defect in every state and federal district
court, sound general design concepts are probably of
more value to the designer than attempts to satisfy
legal "definitions," which may be correct
in one jurisdiction and incorrect in another.
The "restatement of torts," the personal
injury attorney's Bible, provides that a product is
unreasonably dangerous and hence defective if the article
sold has hazards that the ordinary consumer could not
know about with the knowledge common to the community
about the product's characteristics. This test is objective
and does not depend upon the actual knowledge of the
What is safe? The designer tests are likewise objective;
the development of "safe" products is a process
much more standardized than the subjective definition
of "safe" by a jury. A primary consideration
is the "risk/benefit analysis" that provides
that a dangerously defective product is one that a reasonable
person, knowing of its harmful character, would not
sell to the public. Thus, the question is simply whether
the manufacturer is negligent by selling the product,
knowing the risks involved. For example, concentrate
sulfuric acid makes a wonderful drain cleaner and solvent,
but is so dangerous in non-industrial settings that
risk of harm to a housewife or child far outweighs its
superiority as a drain cleaner. Thus, alkali chemicals
are more acceptable for home use.
Simply stated, do not design a machine with a pinch
point if the item can be made equally effective without
endangering the operator's fingers. Charcoal lighter
fluid should ignite charcoal but not be ultra-hazardous
to people or personal property. These basic examples
can and must be extended to the complex products of
the '90s. A faulty micro-chip, electrical component,
or hydraulic system can endanger a manned space flight.
Indeed, the failure of several related products in our
defense systems could bring us to the brink of nuclear
conflict. Most aviation disasters are precipitated by
a combination of design defects and human error.
Anticipate problems. The potential for significant
damage or serious injury is a practical yardstick that
should be applied to the products you design and manufacture.
Use imagination. Not only should products meet or exceed
all relevant industry and government codes, regulations,
and safety standards, but the design team must try to
anticipate any potential factor that might precipitate
All reasonable possible design alternatives should
be evaluated; every foreseeable way that the product
might be misused or abused must be identified and the
unsafe, potentially hazardous design feature eliminated.
If foreseeable dangers cannot be designed out, the conspicuous,
clear, comprehensive, permanent warnings must be affixed
to the product where feasible, or at least accompany
it in the manual.
Anticipation, in the legal sense, is a critical attribute
of today's successful designer. The "absent-minded
professor" image and approach will result in lawsuits
and adverse verdicts related to your products. The engineers
of the '90s must develop a basic understanding of product
liability litigation, and more specifically, the legal
pitfalls of design engineering.
Q: What is the legal definition of a product
A: In states following strict liability
law, a defective product is one that is defective and
unreasonably dangerous to a user when sold. The defect
is any deficiency in the product which may cause it
to fail and result in injury. Even asbestos has been
found defective because of the harm it may cause to
human tissue, although no obvious defect is in asbestos.
Q: Is a designer or manufacturer under an absolute
duty to sell only defect-free products?
A: No. However, the law of strict
liability holds the manufacturer liable for defects
in products which cause harm. The product defect must
make the product unreasonably dangerous to the user.
If the user is injured but, there is no defect nor is
the product unreasonably dangerous the manufacturer
is not liable. The defect must be one which the manufacturer/designer
knew of or should have known about at the time of sale.
If the defect was latent and not discoverable nor reasonably
avoidable by the designer, there may be no liability.
Q: If I design a component product which is
free of any defect, but is later incorporated into a
product which is defectively designed? Am I responsible
if the product fails?
A: No. The component manufacturer
will only be held liable when there is evidence that
that particular component was defective or unreasonably
dangerous. However, it is useful for the component manufacturer
to have an indemnification agreement with the final
product manufacturer to assume the defense of any lawsuit
not caused by the component manufacturer's negligence
or breach of warranty.