The patent holder must prove by a preponderance of the evidence (that it is more likely than not) that the defendant either directly infringed a claim of the patent, contributed to another’s infringement, or induced another to infringe.

For more information regarding the types of infringement, please see Types of Patent Infringement

In a case of direct infringement, the patent holder must prove that the defendant made, used, sold, offered for sale or imported the claimed invention. Direct infringement can be proven through literal infringement or through the doctrine of equivalents. Literal infringement occurs when a claim of the patent is a direct match when compared to the accused device or process. Under the doctrine of equivalents, infringement may be found where an element of the accused device, while not a direct match, is interchangeable with what is claimed. In other words, an accused product infringes if the equivalent element does the same work in substantially the same way to accomplish substantially the same result as the patented product or process.

In a case of contributory infringement, the patent holder must prove that the defendant sold, offered for sale, imported or exported a component that is a material part of a patented invention, and that the defendant knew that the component was made or adapted for use in the infringing product.

In a case of inducement, the patent holder must prove that the defendant actively induced another to directly infringe the patent holder’s patent, knowing that the acts they induced constituted patent infringement, and their encouraging acts actually resulted in direct patent infringement. 

This requires that the defendant knew of the patent.