1) A device or method may infringe a claim literally or by equivalence.

2) A device or method that infringes a dependent claim in a patent must infringe the independent claim on which the dependent claim is directly or indirectly dependent. Therefore, if a device or method does not infringe a valid independent claim, it cannot infringe a claim dependent on the independent claim.

LITERAL INFRINGEMENT

For a device or method literally to infringe a claim in a patent, it must exhibit for each limitation of the claim a feature that falls within the literal ambit of the words that define the limitation. That is, for each limitation of the claim, the device or method must have a feature which is included in the class of features identified by the literal words that define the limitation. For example, if a claim recites a limitation of a “bolt” and a potentially infringing device comprises a “rivet” in place of a bolt, the rivet is not within the literal ambit of “bolt”, because whereas the bolt and the rivet may both generically described as fasteners, the word bolt defines a species of fastener that does not include rivets.

LIMITATION ON LITERAL INFRINGEMENT

The Reverse Doctrine of Equivalence may limit the reach of literal infringement. The U.S. Supreme Court noted that infringement may be avoided despite literal infringement, under what has subsequently come to be known as the reverse doctrine of equivalents:

“…, where a device is so far changed in principle from a patented article that it performs the same or a similar function in a substantially different way, but nevertheless falls within the literal words of the claim, the doctrine of equivalents may be used to restrict the claim and defeat the patentee’s action for infringement. Westinghouse v. Boyden Power Brake Co., 170 U.S. 537, 568, 18 S.Ct. 707, 722, 42 L.Ed. 1136” (Graver Tank & Mfg. Co. v. Linde Air Prod. Co., 339 U.S. 605, 608, 609 (1950)).

INFRINGEMENT UNDER THE DOCTRINE OF EQUIVALENTS (DOE)

If a device or method does not literally infringe a claim in a patent because a limitation in the claim as literally recited is not present in the device or method, the device or method may still infringe the claim under the judicially established US Doctrine of Equivalents as set out by

the US Supreme Court (Graver Tank & Mfg. Co. v. Linde Air Prod. Co., 339 U.S. 605, 608, 609 (1950)) if an element present in the device or method is an equivalent of the missing limitation.

For a device or method to infringe a claim by equivalence, precedent requires that each limitation of the claim find an equivalent feature in the device or method (Warner-Jenkinson Co. v. Hilton Davis Chem. Co., 520 U.S. 17, 39 (1997)). An element may be determined to be equivalent to a missing limitation if:

1) “the only differences between the two are insubstantial”, (Honeywell Int’l Inc. v. Hamilton Sundstrand Corp., 370 F.3d 1131, 1139 (Fed. Cir 2004)) (bold face added); or

2) “the element performs substantially the same function in substantially the same way to obtain substantially the same result” (Schoell v. Regal Marine Indus., Inc., 247 F.3d 1202, 1209-10 (Fed. Cir. 2001)) (bold face added).

The above-noted two tests are conventionally referred to as the “insubstantial differences” test and the “function, way, result” (“FWR”) test, respectively. The Court of Appeals for the Federal Circuit in May 2017 discussed the appropriateness of the two tests under different circumstances noting that the Supreme Court acknowledged that “the suitability of the two tests may vary, depending on the circumstances of the case, 520 U.S. at 40 (“Different linguistic frameworks may be more suitable to different cases, depending on their particular facts.”)” Mylan Institutional LLC, Apicore US LLC, v. Aurobindo Pharma Ltd., Aurobindo Pharma Usa Inc., Auromedics Pharma LLC, (2017).

LIMITATIONS ON THE DOE

The reach of the DOE may be reduced and the doctrine not applicable if the doctrine of claim vitiation or the Festo presumption applies.

1) Doctrine of claim vitiation

Under vitiation, it is not permissible to find that a device or method infringes a claim by equivalence if to do so the claim language must be so distorted as to completely eliminate – that is “vitiate” – a claim element.  “It is important to ensure that the application of the doctrine, (DOE) even as to an individual element, is not allowed such broad play as to effectively eliminate that element in its entirety” (Warner-Jenkinson Co. v. Hilton Davis Chem. Co., 520 U.S. 17, 39 (1997)) (parenthetical acronym “DOE” added)

However, a contention of vitiation cannot be supported, and a device or method determined not to infringe a claim by simply noting that the device or method is missing an element of a claim:

“Courts should be cautious not to shortcut this inquiry by identifying a “binary” choice in which an element is either present or “not present.” Stated otherwise, the vitiation test cannot be satisfied by simply noting that an element is missing from the claimed structure or process
because the doctrine of equivalents, by definition, recognizes that an element is missing that must be supplied by the equivalent substitute. … there is a genuine factual issue that the accused device, while literally omitting a claim element, nonetheless incorporates an equivalent structure.” Deere & Co. v. Bush Hog, LLC, 703 F.3d 1349, 1356 (Fed. Cir. 2012)) (ellipses indicating deleted text, added)

2) The Festo Presumption

Under FESTO if a narrowing amendment to a claim limitation is made for reasons related to patentability, the rebuttable presumption holds that the amendment relinquished claims to equivalents of the amended limitation and the claim may not be able to benefit from DOE (Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. 722 (2002)).