What are the Elements of a Patent Infringement Claim?

Patent law protects inventors’ exclusive rights to the use or sale of their inventions. A patent owner can file a civil lawsuit to recover damages for past infringement and obtain injunctions against further infringing activities. Proving patent infringement in court requires a plaintiff to prove two broad elements: ownership and validity of the patent, and infringement of the patent by the defendant.

1. Ownership of a Valid Patent

The first general element of a patent infringement claim requires proof of two specific sub-elements: ownership of the patent in question, and the patent’s validity.

Ownership of a Patent

The U.S. Patent and Trademark Office (USPTO) may issue patents to inventions and discoveries that meet the criteria found in federal law. Unlike some other forms of intellectual property, no common-law protection exists for patents in the U.S. Instead, registration with the USPTO is the only way to prove ownership.

Since patents and patent rights can be transferred and assigned, proving ownership of a patent may require a considerable amount of documentation. Any error or defect in a written assignment can affect the ability to bring a cause of action for patent infringement.

Validity of a Patent

Under federal law, patent protection is available for machines, processes, and other inventions that are “new and useful,” “novel,” and “non-obvious.” Registration with the USPTO involves an extensive review process before approval. Issuance of a patent therefore creates a presumption of validity. A defendant can challenge the patent on a variety of grounds, so a plaintiff should be prepared to show that the patent is valid.

Possible grounds for challenging the validity of a patent may include:

  • The patented invention is not novel because of prior art;
  • The patented invention consists of obvious subject matter, based on prior art;
  • The patent claims are so unclear or ambiguous that they “fail to inform, with reasonable certainty,” people with knowledge of the subject matter involved (Nautilus, Inc. v. Biosig Instruments, Inc., 572 U.S. 898 (2014)); or
  • The patent holder omitted information or provided inaccurate information when applying to the USPTO.
2. Infringement of the Patent by the Defendant

The second general element of a patent infringement claim consists of three specific sub-elements: the identity of the infringer, the specific act of infringement, and the similarity to one or more patent claims.

Identifying the Infringer

A patent infringement lawsuit must name every alleged infringer as a defendant. This can be more complicated than it sounds, especially when multiple individuals, businesses, or organizations are involved. If the alleged infringement involves one part of a larger product, with multiple entities collaborating in its design, production, or distribution, a patent holder must state which entities were involved, and then demonstrate how they were involved.

Identifying the Infringement

Federal patent law defines patent infringement as “mak[ing], us[ing], offer[ing] to sell, or sell[ing]” a patented invention. It also includes “actively induc[ing] infringement of a patent.” A patent infringement lawsuit must identify one or more distinct acts that constitute infringement.

An allegedly infringing act generally must have occurred within the U.S. for federal law to apply, although there are some exceptions. For example, federal law states that “suppl[ying]...all or a substantial portion of the components of a patented invention” from the U.S. without authorization from the patent holder can constitute patent infringement. The U.S. Supreme Court held in WesternGeco LLC v. ION Geophysical Corp., 585 U.S. ___ (2018), that a plaintiff can recover lost foreign profits as damages for this type of infringement.

Comparison of Patent Claims

The final sub-element in establishing infringement requires a close examination of the patent claims. The language of a claim is important, as is any prior enforcement history. Courts typically use the plain-language meanings of the terms used in a patent claim, unless the patent provides more specific definitions.

For each claim that has allegedly been infringed, the plaintiff must show how the defendant’s invention or product infringes that claim. The comparable elements do not need to be identical. The “doctrine of equivalents” states that infringement occurs when each element of a patented invention is equivalent to an element in the allegedly infringing invention. See Warner-Jenkinson Co. v. Hilton Davis Chemical Co., 520 U.S. 17, 30 (1997). This doctrine is subject to several limitations based on factors like the plaintiff’s past prosecution of the patent.