Literal patent infringement

Patent infringement analysis involves basically two steps claim constmction, and comparison of the accused product to the properly constmed claim. In the first step, which is exclusively a matter of law for the court, each asserted claim is constmed to determine its scope and meaning. In the second step, a fact finder compares each properly constmed claim to the accused device, to determine whether all of the claim limitations are present in that device, either literally or by a substantial equivalent. 

If an accused device does not literally infringe a patent claim because it lacks some element of that claim, it may infringe under the doctrine of equivalents if it contains some element that is insubstantially different from the claim element which it lacks. Warner-Jenkinson Co., Inc. V. Hilton Davis Chemical Co., 520 U.S. 17, 35-36 (1997). 

Sometimes patent protection may extend beyond the literal wording of what was initially protected. An example may illustrate this. In the 1970s, Eli Lilly s very successful antibiotic Cephalexin was the subject of a patent. Squibb then came onto the market with Cephradine. The Courts found that Squibb was infringing Lilly s patent on the basis that Squibb s Cephradine contained a few percent of Cephalexin. Reportedly, Squibb settled by agreeing to a royalty. 

Japan and the USA formally limit the protection of a patent to what is literally defined by the claims. In the USA "equivalents" are also covered by a patent, i.e. infringers using equivalents may be sued. Equivalence is defined by the US Supreme Court as doing "substantially the same thing in substantially the same way to get substantially the same result" (Graver vs. Linde, 339 U.S. 605, 608, 1950) as a patented invention without literally infringing it. 

The "Doctrine of Equivalents" applies to the interpretation of claims to establish infringement of existing patent rights in those cases where there is no literal infringement. Anything that comes under the definition of equivalents would have been patentable at the priority date (and should be included in the claims). Thus the Doctrine cannot be used as an argument to negotiate broader claims for a patent at the time of application or prosecution (Kushan, 1992). 

To define literal infringement, the plain language of the patent claims must first be properly interpreted. This is accomplished by consideration of the ordinary meaning of the language of the claim, the patent... 

Literal infringement focuses on individual claim elements rather than on the invention as a whole. Whether a product infringes the claims of the patent depends on whether the product literally embodies each and every element of those claims. Each element of a claim is material and essential to the definition of the invention. If the product or process does not use even one element of the patent claim, it will not literally infringe the claims. However, the accused infringer usually cannot escape liability for literal infringement merely by adding elements that are not found in the patent claims if each element cited in the claims is found in the product or process under investigation. 

Although the requirements of literal infringement may not be satisfied, infringement may still be found under the Doctrine of Equivalents. This doctrine is satisfied when the product in question contains elements identical or equivalent to each claimed element of the patented invention. ... 

The United States Court of Appeals for the Federal Circuit subsequently upheld the decision of the District Court with respect to both issues of literal infringement and infringement under the doctrine of equivalents. With regard to the issue of literal infringement, the Court of Appeals reasoned that for a product to literally infringe a patent claim, the product in question must contain each limitation of the asserted claim. In other words, the accused product must contain each element of the patented composition to constitute... 

The doctrine of equivalents gives a court the ability to effectively expand the scope of a patent claim beyond the literal language of the claim. Otherwise, a party who copies a patent s inventive concept, but makes some trivial or obvious change, would avoid legal infringement. The doctrine of equivalents is a... 

If you are on the plaintiff side, you analyze the language of the claims as interpreted by the specification (the main part of the patent). The judge may define the meaning of the claims. You examine and test the accused device to determine whether it is covered by the claims. If so, you write an opinion that the accused device infringes the patent claims. Infringement may be literal the words in the claim may describe the device. The infringement may be under the doctrine of equivalents if the accused device or process performs substantially the same function, and operates in substantially the same way to achieve substantially the same... 

Conversely the, by making certain that at least one element/limitation of the patented claim is missing in the designed around product, process or apparatus, a competitor may avoid literal infringement. Also, by operating at conditions outside the ranges specified in the patent claims, a competitor would not infringe the patented invention. 

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