In a products liability design defect action, evidence establishing the defectiveness of a product is paramount to a plaintiff’s case. Some jurisdictions require the plaintiff to bear the burden of offering evidence of a safer design (often defined as a “reasonable alternative design” or “feasible alternative design”). Similarly, plaintiffs may be required to produce evidence that a manufacturer of an allegedly defective product was on notice of the product’s defect and failed to remedy the product. Often, the potential evidence, for either side, that is available through the teachings of patents is overlooked. Conducting a patent search and an investigation of the state of the patent art may yield fruitful evidence regarding the defect or relative safety of the product at issue in a products liability action. But first some background to set the environment for how patents become patents.

The primary advantage of a patent is to secure to the inventor the right “to exclude others from making, using, offering for sale or selling the invention throughout the United States.” However, the patent applicant must give something to the public in return for this period of exclusivity. The patent applicant is required to disclose sufficient information in the patent application to support the subject invention and to justify the patent’s claims. The drawings and specification of a patent application must include (a) a specification as set forth in 35 U.S.C. §112; (b) a drawing as expressed in 35 U.S.C. §113; and (c) an oath by the applicant as expressed in 35 U.S.C. §115. While all of these things are required, it must be remembered throughout the remainder of this article and any use of patents that the U.S. patent examiner does not pass on the commercial merit or the practicality of producing the invention. The examiner is concerned with the applicant meeting the statutory requirements for a patent rather than the likelihood of the invention being a market success. Accordingly, the patent search needs to be conducted by someone with an understanding of the technology and the specific problem or defect at issue.

In the examination of the patent application, the patent examiner applies procedural guidelines to be sure the applicant’s specification complies with the statute by setting forth “a written description of the invention, and … the manner and process of making and using it, in … full, clear, concise and exact terms as to enable any person skilled in the art … to make and use the same.” The examination guidelines, called the Manual of Patent Examining Procedure, elaborate on the content requirements of a specification. MPEP §6.02(f) provides that a specification should include the background of the invention, including “a statement of the field of art to which the invention pertains, as well as a description of the related art, and if applicable, references to specific related art and problems involved in the prior art which are solved by the applicant’s invention.” The specification should also include a brief summary of the invention, a brief description of the drawings, a detailed description of the invention and the claim(s) made by the inventor. If the process is working properly, the specification of a patent should provide a wealth of information about the improvements in the state of the art. Because it is not practical to review all available patents, a search should be made in a relevant date range and selected patent specifications should be identified for further investigation and analysis with a view toward identifying relevant evidence in support of the plaintiff or defendant’s theory in the defective design case.

A party litigant who locates a relevant patent needs to consider how to use that information within the context of the specific fact pattern. Consider a plaintiff who finds a patent for an alternative design that provides a detailed identification of a prior art defect that is relevant to the case. This may appear to be detrimental evidence to the defendant’s case. However, the plaintiff seeking to utilize that patent must understand its evidentiary value and proper admission as trial evidence. The naked introduction of a patent to establish a basis for the proposition that a “reasonable” or “feasible” alternative design exists is likely to be meaningless. In Mallory v. Hobbs Trailers, 554 So.2d 966, 971 (Ala. 1989), the plaintiff failed to present any testimony or evidence regarding the authenticity of the patents, the feasibility of the devices described by the patents, whether the devices had been shown to be workable in the industry or that the patented device had been reduced to practice and tested.

In contrast, a correct use of patent evidence is illustrated in Hodges v. Mack Trucks, 474 F.3d 188, 196-98 (5th Cir. 2006). Here, the plaintiff’s expert examined several hundred door-latch patents publicly available from the U.S. Patent and Trademark Office to determine whether suitable alternative designs existed. After finding possible alternative designs, he examined how each performed compared to the Mack latch, and determined the maximum amount of force required before the Mack latch would fail. He compared the results and determined the Mack latch was defective because it was weaker than other latches used on similar vehicles by 75 to 80 percent. He concluded it would have been easy and inexpensive for Mack to use the comparable latch, and offered evidence of its existence and use in fire trucks at the time the Mack latch was manufactured. The court accepted his testimony and found the use of patent evidence to be relevant and reliable.

The admission of patent evidence is often within the trial judge’s discretion. If a patent is admitted, the opposing party is likely to attack the feasibility of what the patent claims or states. A party will often attempt to refute the patent’s teaching by showing the patented invention was never manufactured or tested, accepted the relevant industry, was quickly replaced by some later invention or simply is not relevant to the facts of the case at hand.

The importance of matching the patent evidence to facts of the case cannot be overstated. As in any case, the various points and counterpoints made at trial must bear on the issues being tried. An oversight in matching the patent teachings to the issues relevant to the defective product can be fatal. This was plainly demonstrated in GMC v. Harper, 61 S.W.3d 118 (Tex. App. 2001). In this case, GMC appealed the trial court judgment and a staggering jury award of $47.5 million. The plaintiffs may have won the battle to admit the patent evidence on appeal, but suffered a severe blow in the war, as both the GMC and non-GMC patents were found to be unsupportive of the jury’s finding as to defect or causation. The patents discussed the elasticity of nylon seatbelts, whereas the actual seatbelts in the vehicle were made of polyester. Moreover, the patent discussing the alternative webbing technique was never tested or actually purchased by any vehicle manufacturer. The court reversed and rendered a take-nothing judgment for GMC. This case demonstrates the risks and benefits of using patent teachings in any products liability case.

A defendant may also rely on evidence in a patent to refute a claim that a reasonable alternative existed at the time the allegedly defective product was manufactured. Evidence that the patented design did not perform as anticipated, failed preproduction testing or was never implemented due to its failure to meet governmental regulations will reinforce a defendant’s claim that no acceptable alternative existed. Moreover, it will serve as evidence that the accused manufacturer was actively engaged in improving the safety of its product. In GMC v. Sanchez, 997 S.W.2d 584, 596 (Tex. 1999), GMC presented evidence of engineering work to modify and improve its transmissions, including a 1989 patent application describing a design to address a “mis-shift” problem. This 1989 design alternative could not be implemented due to federal standardization guidelines in vehicle shifting patterns. With this background, GMC was able to use this patent as rebuttal evidence to the plaintiff’s claim that GMC was consciously indifferent to a known serious risk.

In a like manner, the statutory exclusivity accorded a patented invention may suggest that an alleged alternative design actually was not available for use at the time in issue. In Delphen v. Dept. of Transp. & Dev., 657 So. 2d 328, 334 (La. Ct. App. 1995), the court noted that a bicycle wheel retention device could only be used by the company holding the patent, and other similar devices were not developed or feasible at the time. This holding illustrates the importance of considering the details associated with presenting a patent’s teachings as feasible and available.

The use of patents also raises evidentiary issues. Statements or information contained in a patent may be vulnerable to hearsay objections. In a federal court, a patent will generally be admissible under the public records exception to the hearsay rule. See Standard Havens Prods. v. Gencor Industries, 953 F.2d 1360, 1372 (Fed. Cir. 1991) (a patent qualifies as a public document and, if relevant, should qualify as a public records exception to the rule against hearsay). Statements contained within a patent or patent application may constitute hearsay within hearsay, and must conform to an exception to the hearsay rule. Often, these statements will be admissible under Fed. R. Evid. 801(d)(2)(D) as a party admission. See Church & Dwight v. Huey, 961 S.W.2d 560, 570 (Tex. App. 1997) (descriptions of problems in the prior art contained in patent applications were filled out by Church & Dwight, and are admissible as party admissions). Furthermore, patent applicants may be admissible as nonhearsay, not to show the truth of a deficiency of a product as described in the patent, but to show knowledge of such a deficiency.

In Wielgus v. Ryobi, No. 08 CV 1597, 2012 U.S. Dist. LEXIS 67927 at 9-12 (N.D. Ill. May 16, 2012), the court denied the defendant’s motion in limine to preclude statements contained in a 2004 saw blade patent. The patent application included the inventor’s attempt to differentiate his proposed design from the traditional guard designs and described the guard that came with the product on trial as “flimsy” and “difficult to use.” The court further ruled these statements would survive a Rule 403 motion, concluding the concessions were relevant and not unfairly prejudicial.

As seen above in Harper, the appellate court found that although patents for inventions involving energy-absorbing seatbelts were admissible under the public records exception to the hearsay rule, the statements not belonging to GMC within some non-GMC patents constituted inadmissible hearsay. However, because GMC only generally objected and failed to request a limiting instruction, the patents were admissible in full without being redacted. Further, a patent assigned to GMC constituted an admission of a party opponent. Harper demonstrates that statements made in patents not attributed to the manufacturer may constitute inadmissible hearsay. A party opponent must properly object to these statements and seek a limiting instruction to prevent these statements from potentially damaging its case. Understanding the rules of evidence in the admissibility of patents is essential to their successful use.

State evidence rules may vary, and it is important to consult each state’s specific rules in determining the admissibility of a patent. See Majdic v. Cincinnati Machine, 537 A.2d 334, 340 (Pa. Super 1988) (“With respect to the patents, the learned treatise exception has no application. The assurances of trustworthiness which are intrinsic in scholarly treatises do not exist where patents are concerned. Unlike learned treatises, patents are not necessarily propounded by an expert in the field in which the patent applies; rather, they may be obtained by any individual with an original idea. Moreover, they are not generally subject to the type of criticism and analysis which learned treatises usually undergo.”) Advocates must understand the relevant rules of that court for admissibility of patent evidence.

Practice Tips

When contemplating the use of patent evidence, it is important to consider the following:

• Conducting a patent search to determine if alternative designs were available at any time relevant to the product at issue.

• Determining whether the proposed alternatives were ever produced, tested or commercially implemented.

• Hiring a technical expert in the specific product field or industry to assist in focusing the search process and determining how to use what is found.

• Using an expert to introduce the patent evidence.

• Understanding the jurisdiction’s evidence rules, especially as they may apply to hearsay and experts.

Anthony S. Volpe is a shareholder at Volpe & Koenig and has corporate and private practice experience in securing, licensing and enforcing all aspects of intellectual property rights. His patent work includes appeals before the USPTO Board of Patent Appeals and interferences and international trade commission, prosecution of patent applications, rendering opinions regarding patentability and enforcement of patent rights. 

Max S. Morgan is a law clerk at the firm and a third-year law student at Rutgers School of Law-Camden. He can be contacted at