If a patent is analogized to real property, the claims correspond to the boundary recited in the deed. Invasion of the boundary of a landowner's real estate is called trespass, while invasion of a patentee's claims is called infringement. Unlike a trespass, patent infringement is a statutory wrong and is governed by federal law. A determination of patent infringement involves a two-step process. First, the claims are analyzed by studying all of the relevant patent documents.
Infringement can be direct, indirect, or contributory.
Anyone who makes, uses, or sells the patented invention is a direct infringer. If a person actively encourages another to make, use, or sell the invention, the person so inducing is liable for indirect infringement. Contributory infringement can be committed by knowingly selling or supplying an item for which the only use is in connection with a patented invention. Good faith or ignorance is no defense for direct infringement, but it can be for indirect or contributory infringement. By the Government Infringement, by the Government, of privately owned patents, is governed by 28 U.S.C. 1498, which provides that a suit against the Government in the U.S. Court of Federal Claims is the exclusvie remedy for patent holders who allege their patented invention has been infringed by the U.S. Government or by one acting for the Government.