patent infringement

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Patent infringement is the unlawful use, selling, or copying of a patented  invention. United States patent law protects such inventions.

A patent is a type of intellectual property that the inventor could seek protection by filing a patent application. Other forms of intellectual property that are protected include copyrights and trademarks. While the protection for copyrights and trademarks is automatic, one must officially file an application to receive protection under the patent law. The process of drafting, filing, and negotiating with the Patent and Trademark Office (USPTO) for securing patent rights and protection is called patent prosecution. The patent protection covers the physical or intellectual invention, as well as the process of the invention. The patent examiner looks into the invention to determine whether the patent law should protect the invention.

For the invention to enjoy protection, the violation must occur within the United States. However, the unlawful use or copying of the invention could be a violation that invokes the protection of the invention if the copied product gets imported into the United States. If an individual induces another to infringe an invention protected by patent law, then the inducer could be sued under patent infringement as well.

35 U.S.C. § 271 lays out the conduct that may amount to patent infringement. Generally, there are two categories of patent infringement: direct and indirect infringement. 

  • If the accused manufactured, sold, attempted to sell, or imported the invention without permission, a direct infringement occurs. 
  • If the accused actively induces a third party to manufacture, sell, attempt to sell, or import the invention without permission, indirect infringement (contributory infringement) occurs.

A patent infringement lawsuit is a civil case. The patent owner typically sues the infringer to enforce the patent against the protected invention. The court determines whether the acts of the defendant of the lawsuit amount to infringement. The court uses a two-step test for the determination. 

  • The court first looks into a process called claim construction. 
    • During claim construction, the court examines the claim language, the invention’s written description, extrinsic evidence for patent comprehension, and the previous prosecution history of the invention. 
  • Then, the court decides whether the particular item subject to patent infringement claim actually does infringe on the invention. 
    • For this, the court looks into the three elements of a patent: usefulness, novelty, and non-obviousness
      • The court evaluates the item through the three elements, comparing them to the patent-protected invention. 
    • If the court determines that all three elements are the same as the protected invention, then the court finds that there is an infringement.

If the court determines that the accused product violates only some of the elements or that the differences are visibly insignificant, then the court looks into the doctrine of equivalents. The doctrine of equivalents states that there is an infringement if the original invention and the item in question are sufficiently equivalent in their function and how they function. The court may find infringement if two of the elements are interchangeable, and the person with the ordinary skill in the art of the invention would have known that such elements are interchangeable. The court can also implement the triple identity test to determine whether the differences are immaterial. Under the triple identity test, if the features that consist of the infringement claim perform pretty much the same function for both products in the same way materially, resulting in basically the same outcome, then the differences are immaterial.

See: Graver Tank & Mfg. Co. v. Linde Air Prods. Co. (1950), Litton Systems v. Honeywell (Fed. Cir. 1990), Amgen Inc. v. Sanofi (2023), and Oyez Patent Cases

See also: infringement (of utility patent)

[Last updated in January of 2024 by the Wex Definitions Team]