Infringement not found in patent case involving fracking mud storage container. SANDBOX v. PROPPANT EXPRESS

A patent is a set of exclusive rights granted to the inventor of an invention. To obtain a patent in the United States an inventor must file a patent application with the United States Patent and Trademark Office. The patent application is reviewed by a patent examiner at the United States Patent and Trademark Office to ensure that the invention described in the patent application meets all the criteria for patent protection. If the patent application meets all the criteria for patentability then the inventor will be granted a patent on the invention.

A patent grants its owner the exclusive right to make, use, sell and import the invention claimed in the patent. If someone other than the patent owner attempts to exercise on of these exclusive rights, that is considered patent infringement. To combat patent infringement a patent owner can file a complaint in United States Federal Court. A patent infringement lawsuit proceeds much like any other lawsuit however, there is an added step.

After discovery, the court will perform a Markman hearing to interpret the claims in a patent. Patent infringement cases usually turn on how a court interprets the claims of a patent in a Markman hearing. Patent claims may be written in English, however the words in the claims do not always match their dictionary definition.

The words used in the claims are interpreted in light of the intrinsic evidence of record, including the written description, the drawings, and the prosecution history. The claims are interpreted from the perspective of a person having ordinary skill in the art (PHOSITA). A PHOSITA is a hypothetical person that is familiar with the technology that the invention is related. The PHOSITA is deemed to read the claim term not only in the context of the particular claim in which the disputed term appears, but in the context of the entire patent, including the specification. The prosecution history may also be looked to in order to supply additional evidence of a claim term’s intended meaning.

Courts may also consider extrinsic evidence in claim construction, however such evidence is generally of less significance than the intrinsic record. The ultimate construction of a claim term is a legal question reviewed de novo, while underlying factual determinations made by the district court are reviewed for clear error.

SANDBOX LOGISTICS LLC v. PROPPANT EXPRESS INVESTMENTS, 19-1684 (C.A.F.C. 2020) is a case which turned on claim construction. The patent in this case claim a storage container for proppant. Proppant is the slurry used in fracking. With the dramatic expansion of fracking in the United States, the technology surrounding the storage and dispensing of proppant is closely guarded.

Plaintiff owned several patents related to proppant storage containers. Plaintiff sued Defendant for patent infringement. After the Markman hearing the parties stipulated that Defendant did not infringe and the District Court entered judgement in favor of Defendant. Plaintiff then appealed the District Court’s claim construction. Specifically the Plaintiff did not agree with the District Court’s definition of “bottom” and “structural member”.

The Court of Appeal for the Federal Circuit heard the appeal and affirmed the District Court’s judgement. The Federal Circuit reviewed the prosecution history for the patent and noted that the patent claims were amended to overcome a rejection. The amendment added a “bottom” the patent claims and the Patent Examiner noted that he interpreted this to mean a “bottom wall” of the container. Because the Plaintiff did not debate this point during patent prosecution the District Court properly interpreted the claim.

With respect to “structural member” the Plaintiff asserted that the side walls of a container alone could qualify as structural members. Again prosecution history was used to contradict this assertion. Plaintiff had amended its patent claims to overcome prior art and in that amendment added “structural members” to strength the side walls of the invention. Thus the District Court correctly found that “structural members” were separate and distinct from the side walls of the proppant container.

Because the District Court did not make a clear error in its claim construction the Federal Circuit affirmed the judgement.

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