The doctrine of equivalents is unavailable as a matter of law “if a theory of equivalence would entirely vitiate a particular claim element.” Be careful not to draft or amend a claim element in such a way that would unduly limit it to a particular kind of element (e.g., one that imparts lateral movement) that operates in a fundamentally different way from other viable alternatives (e.g., one that imparts rotational movement). The doctrine of equivalents will not be able to reach those alternatives.
Background / Facts: This case concerns “trocars,” which are a type of surgical device used in laparoscopic surgery where the surgeon uses thin tools to operate through several small incisions. Trocars are placed in each incision to provide airtight ports through which instruments may be passed into the abdominal cavity. The trocars also allow surgeons to inflate the patient’s abdominal cavity in order to provide space for the doctor to operate. The patent claims a seal assembly that can move laterally but not axially, which allows the trocar to accommodate a wider variety of tools. The accused assembly seal provides a similar advantage, but it does not move laterally – it is a hemisphere that rotates in place.
Issue(s): Whether allowing rotation to be equivalent to side to side movement under the doctrine of equivalents would vitiate the free lateral movement limitation.
Holding(s): Yes. “While the claims require free lateral movement of the instrument seal assembly, the instrument seal assembly of the [accused device] does not possess free lateral movement. Indeed, the instrument seal assembly of the [accused device] not only does not move freely laterally, it does not move laterally at all – rather it is fixed laterally and rotates in place. Accordingly, allowing [the patentee] to capture the accused instrument seal assembly through the doctrine of equivalents would vitiate the claim limitation requiring ‘free lateral movement’ of the instrument seal assembly.”