Eye Therapies v. Slayback: Federal Circuit Abandons Standard Transition Construction

by Dennis Crouch

Eye Therapies v. Slayback offers a concerning example of the Federal Circuit departing from well-established patent claim construction doctrine. In this case, the court abandoned the standard interpretation of the transitional phrase “consisting essentially of” after finding that the patentee’s prosecution statements created sufficient grounds to narrow claim scope.  As I explain below, in my opinion, this result conflicts with the court’s own Ecolab precedent and threatens to shift claim-transition interpretation from its traditional position as a canon of claim construction.