Question 39
Domain 5: Patent Ownership, Infringement, and EthicsUnder the doctrine of equivalents, when does a claim cover an accused device?
Correct answer: B
Explanation
Under the doctrine of equivalents, a claim reaches an accused device if it has elements that are "substantially the same" as the claimed invention. The test asks whether the device performs "substantially the same function, in substantially the same way, to achieve substantially the same result," which prevents an infringer from avoiding liability through insubstantial changes.
Why each option is right or wrong
A. Only when each claim limitation is literally met
B. When the accused device performs substantially the same function, in substantially the same way, to achieve substantially the same result
The doctrine of equivalents applies when the accused device contains an insubstantial variation of the claimed element, measured by the classic function-way-result test recognized in patent infringement analysis. Courts ask whether the accused device performs the same function, in the same way, to obtain the same result; if so, the claim can reach it even though the literal claim language is not met. This prevents a party from escaping infringement by making only trivial changes to the claimed invention.
C. When the accused device falls within the broadest reasonable interpretation of the claims
D. When the specification describes the accused device as an alternative embodiment