Let us begin by discussing how a utility patent is infringed. Infringement may be direct or indirect.
Direct Infringement: A patent is directly infringed if a product or process incorporates all of the elements of an independent claim of the patent. The independent claim in a patent may have the following format.
1. An apparatus comprising:
Element B; and
Products that incorporate Elements A, B and C literally infringe Claim 1. Conversely, products that incorporate less than all of Elements A, B and C do not literally infringe Claim 1. For example, a product that incorporates Elements A and B but not C does not literally infringe Claim 1. As such, to avoid literal infringement of a patent, one must not literally practice (i.e., make, use, offer for sale or import) all of the limitations recited in the independent claims of the patent.
However, even though a claim of the patent is not literally infringed, infringement can still be found under the Doctrine of Equivalents (a.k.a. DOE). This doctrine stands for the proposition that even if a product does not literally infringe a claim because it does not incorporate one or more of the elements of the claim, infringement can still be found if the product or process incorporates a feature that is insubstantially different with respect to the missing element. As such, a product which incorporates Elements A and B and a feature which is insubstantially different with respect to Element C still infringes the patent under the Doctrine of Equivalents.
To determine whether the element can be broadened under the doctrine of equivalents, the communications between the patentee and Patent Office must be reviewed to determine whether there are any statements or claim amendments that would prevent or limit the application of the Doctrine of Equivalents. The law would not permit a patentee to make statements to the Patent Office that D is a substantial difference compared to element C during review at the Patent Office but argue during litigation that D is actually an insubstantial difference.
Hence, to avoid infringement of a patent, changes to a product or process must be made to avoid literal infringement and infringement under the Doctrine of Equivalents.
Myth: The percentage difference of a product compared to a patented product does not indicate whether the product infringes on claims of the patent. Patent infringement is found either literally or under the Doctrine of Equivalents.
Indirect Infringement: Liability for patent infringement may be found indirectly (1) when one actively induces another to infringe a patent or (2) when one offers to sell … or imports … a component of a patented machine … for use in practicing a patented process, constituting a material part of the invention, knowing the same to be especially made or especially adapted for use in an infringement of such patent, and not a staple article or commodity of commerce suitable for substantial non-infringing use.
I invite you to contact me with your patent questions at (949) 433-0900 or James@OCPatentLawyer.com. Please feel free to forward this article to your friends. As an Orange County Patent Lawyer, I serve Orange County, Irvine, Los Angeles, San Diego and surrounding cities.