Infringement of a patent consists of the unauthorized making, using, offering for sale or selling of any patented invention within the United States or United States Territories, or the importing into the United States of any patented invention during the term of the patent. If a patent is infringed, the patent holder may sue for relief in the appropriate Federal court. The patent holder may ask the court for an injunction to prevent the continuation of the infringement and may also ask the court for an award of damages because of the infringement.

A determination of patent infringement involves a two-step process. First, the court analyzes the claims by studying all of the relevant patent documents. Second, the claims must "read on" the accused device or process. This means that the device or process is examined to see if the patent claims substantially describe it. In this process, the court tests the claims to see whether they describe the accused infringement.

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. A person can commit contributory infringement 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.

Often times in an infringement suit, the defendant raises as a defense the question of the validity of the patent. Despite the Patent and Trademark Office's issuance of a patent, which is a required element of a patent infringement suit, the court hearing the cases decides whether the Office correctly issued the patent or whether the invention or process did not qualify for patent protection. The defendant may also argue that the alleged infringing activity does not, in fact, constitute infringement. A court determines whether infringement occurred primarily by the language of the claims of the patent.

The claims of the patent are a part of the patent's specification that defines the invention. As a whole, the specification serves as a written description of the invention and the manner and process of making and using it. Under the federal regulations described in the Manual of Patent Examining Procedure, the specification must conclude with a distinct claim pointing out what purpose the patented invention or process is designed to serve. In short, the claim provides the subject matter that the applicant regards as his invention or discovery. The claims must find support in the remainder of the specification, such that any claims are clearly related to the description of the invention. The claim becomes important in litigation because, if what a patent infringement defendant is making does not fall within the language of any of the claims of the patent, no infringement exists.

Several other defenses to a claim of patent infringement exist. These include a defense of experimental use, which provides an exception to infringement in cases where public policy should encourage people to improve on patented invention. File wrapper estoppel can limit a claim as a result of something the Office said or did, upon which the defendant relied to his or her detriment. Separate patentability is a defense based on the fact that the accused device has its own patent, suggesting it may be different enough to avoid infringement. In cases where the accused device was public prior to the issuance of the patent, the defendant may be able to take advantage of an anticipation defense. A more practical defense is the one which claims that the damage was so de minimis, or minimal, that damages are not worth litigating.

An extremely popular, and dangerous defense, is the defense of inequitable conduct. This defense asserts that the patent holder participated in some sort of fraud in order to obtain the patent at issue in the case. Inequitable conduct, if successful, can allow a defendant to pursue the patent holder's personal assets to recoup the costs of litigation.

The Office has no jurisdiction, or authority, over questions relating to infringement of patents. In examining applications for patent, the Office makes no attempt to determine whether the invention an applicant seeks to patent infringes any prior patent. An improvement invention may be patentable, but it might infringe a prior unexpired patent for the invention improved upon, if there is one. Regardless, the Office will approve a patent, provided it fulfills the criteria for approval, even if infringement exists.

Many steps may precede the filing of an infringement suit. The first step in resolving a potential infringement case is notifying the infringer by certified mail. Legal experts suggest that the initial notice should be polite, friendly, and firm. This notice should request a meeting with upper management and perhaps suggest the opening of negotiations to allow the potential infringer to license the patent. Infringers should respond to the notice within one month.

While notice is key to any infringement case, it is important that the patent holder carefully draft the notice letter. If the notice letter states as an absolute that the party is participating in patent infringement the accused can then sue the patent holder for declaratory judgment in the jurisdiction where the letter is received. A carefully worded letter can avoid this problem. The danger of declaratory judgment is that it forces the patent holder to litigate, perhaps in a court far away, and perhaps before there is sufficient information for successful litigation.

Once notice has been provided, and the alleged infringer has either not responded or refused offers to enter into a licensing agreement, litigation can begin.

A patent infringement suit always starts in a federal district court, since patents are with the exclusive purview of the federal government. After the decision of the district court, both parties have a right to an appeal to the Court of Appeals for the Federal Circuit. After this appeal, the parties may request review by the Supreme Court, but any such review is made at the discretion of the Supreme Court itself. Therefore, there is no right to appeal to the Supreme Court.

If the United States Government infringes a patent, the patent holder may seek damages in the United States Court of Federal Claims. The Court of Federal Claims, however, cannot enjoin the Government's use of the patented invention. The Government may use any patented invention without permission of the patent holder, but the patent holder remains entitled to obtain compensation for the use by or for the Government.

A patent holder may recover money damages in the form of a "reasonable royalty," which is the amount the patent holder could have earned in licensing the patented technology. Under certain circumstances, the patent owner may recover lost profits as an alternative measure of damages. The court may triple the money damages if it finds that the infringement is "willful" or intentional. Courts often issue injunctions to prevent the infringer's further use and sale of the patented invention.


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