Literal infringement

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). 

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... 

Such variations may fall within the scope of a claim under the doctrine of equivalents. See section 4.4. It is, however, easier to prove literal infringement. Moreover, an original claim of properly expanded scope may have its own scope expanded, based on the doctrine of equivalents. 

Products Co., 339 U.S. 605, 607, 70 S.Ct. 854, 94 L.ED. 1097 (1950). Therefore, under literal infringement, each claim element must be found in the alleged infringing device, product or method. 

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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