Doctrine of equivalents

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). 

Hoechst-Roussel Pharms., Inc., 109 F.3d at 759 ( The relationship between mfringement and the claims becomes even more tenuous under the doctrine of equivalents, where a product is deemed to infringe the patentee s right to exclude even though the product does not fall within the scope of the patent s claims. ). 

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). 

Protein Patents and the Doctrine of Equivalents Limits on the Expansion of Patent Rights (Comment)... 

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. ... 

To determine whether this product possesses elements identical or equivalent to elements of the patented product, many factors may be considered. For example, if this product performs substantially the same overall function in substantially the same way, to obtain the same overall result as the claimed product, the conclusion that the element in question is equivalent is supported. However, this is not the only factor evaluated to analyze the doctrine of equivalents. In addition, known interchangeability of the elements used in the accused product compared with the elements of the claimed product by those skilled in the relevant art supports the conclusion that the element of the accused product is equivalent to the claimed product. On the other hand, evidence of lengthy efforts to design around the claims of the patent supports the conclusion that the accused product is not equivalent to the patented product. 

The Doctrine of Equivalents has recently been severely restricted by the Court of Appeals for the Federal Circuit. In Festo Corp. v. Shoketsu Kinzoku... 

The basic effect of the doctrine of equivalents is to allow the patent owner to expand the scope of protection afforded by the literal language of the claims. However, the doctrine of equivalents does not allow the patent owner to expand the scope of the claims without restriction. The ability of the patent owner to expand the scope of the patent claims is restrained by the prior art and also by the doctrine of prosecution history estoppel. 

The prior art limits the degree to which the claims may be interpreted because the claimed invention cannot be interpreted so broadly under the doctrine of equivalents as to encompass products that were known before the patent owner invented the claimed product. In other words, the claims may not be interpreted as broadly under the doctrine of equivalents as to read on the prior art. 

The doctrine of prosecution history estoppel also limits the degree to which the claims may be interpreted under the doctrine of equivalents. The doctrine of prosecution history estoppel precludes the patent owner from interpreting the claims in a manner that would encompass, within the claim, subject matter that the patent owner surrendered during prosecution of the patent application to achieve issuance of the patent. Any subject matter that the patent owner surrendered during prosecution to obtain allowance of claims made in the application of the patent cannot be reclaimed under the doctrine of equivalents. 

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... 

In a lawsuit involving the Ortho Pharmaceutical Corporation, the issue was whether Ortho s norgestimate infringed the patentee s claims to norgestrel under the doctrine of equivalence.5 Both compounds are progestin-type steroid hormones used as oral contraceptives. The two compounds share the same fused ring core... 

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... 

In 1995 the Federal Circuit addressed basic issues concerning the doctrine of equivalents and held that (l)the determination of equivalents is a fact issue to be resolved by the jury ... 

Further, a composition, device, or process cannot infringe a patent under the doctrine of equivalents where the broader interpretation of the patent claims necessary to cover the accused device or process would also cover "prior art" (i.e., the state of the technology before the filing of the patent application) (190). 

Although the Festo decision would lend certainty to the determination of patent scope, there is concern that it represents an overly rigid approach that will, in effect, severely restrict patent rights. The Supreme Court recently vacated the Federal Circuit s Festo decision and returned the case to the Federal Circuit for further consideration. The claim scope actually surrendered with the amendment will, however, apparently remain an important consideration in applying the doctrine of equivalents and prosecution history estop-... 

Recently the Court of Appeals for the Federal Circuit ruled that when a claim limitation is narrowed during prosecution, application of the doctrine of equivalents to that claim element is completely barred. Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., Ltd., 234. 3d 558 (Fed. Cir. 1999), vacated and remanded, 122 S. Ct. 1831 (2002). Although the... 

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. 

Examples of fact issues include disputes regarding the structure and operation of the accused device, the teachings of the prior art and level of skill in the art, and the amount of damages sustained on account of the infringement. Examples of legal issues include claim interpretation, and whether the prior art prevents infringement under the doctrine of equivalents. 

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... 

If you are on the defendant side, you list reasons why the patent is invalid, for example, it was obvious, not novel, not useful, invented earlier as described in prior art (anticipated), the specification does not have an adequate description of how to implement the invention (lack of enablement), the patent applicant held back important information that he should have provided to the patent examiner and did not tell all (inequitable conduct), or the file history describes how the applicant restricted the meaning of the claims during patent prosecution. Not only the listed reasons above, but in addition that you have actually tested the medical device, and it does not infringe the patent because it does not contain every element of the claim or imder the doctrine of equivalents. 

In his important memoirs On the Constitution of Acids and Salts and Remarks on the Doctrine of Equivalents , Odling, following Williamson, says that all salts — acid, neutral or basic. . . can be referred to the type of one... 

---