Federal Circuit Affirms Non-Infringement in ZTlido Patent Dispute: Clarifying the Limits of the Doctrine of Equivalents
The U.S. Court of Appeals for the Federal Circuit (CAFC) issued a decision Tuesday affirming a judgment of non-infringement entered by the U.S. District Court for the Southern District of Florida in a dispute concerning generic versions of the topical pain patch ZTlido. The panel
WISECODE Take
Many believe that patents protect against any minor formulation changes through the doctrine of equivalents. However, the CAFC's recent ruling in the ZTlido generic case clarifies that patent owners cannot arbitrarily expand literal claim scopes during litigation. In this case, Scilex accused Aveva's generic patch of infringing U.S. Patent No. 9,283,174. Since Aveva did not use the claimed dissolving agent, Scilex relied on the doctrine of equivalents, but the court ruled that n-heptane was not equivalent. This highlights the high risks for companies relying on broad terms in U.S. courts. While physical hardware makers remain unaffected, formulation developers must refine their claims. We suggest two actions: first, explicitly list alternative ingredients in patent drafting rather than relying on functional terms; second, during design-around, closely examine the prosecution history to identify any limiting amendments. Ultimately, claim precision dictates litigation outcomes; vague terms fail to provide real protection in court.
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