In a recent post-trial opinion, district judge Sue L. Robinson emphasized the importance of a patentee’s conduct during prosecution for later claims of infringement. In the underlying action, the patentee alleged that defendant’s ANDA product, which covered an oral tablet that dissolved without water, contained distinct disintegrating and swelling agents, as required by the patent.
The Court disagreed, resting its conclusion of non-infringement in part on the patentee’s own disavowal of the purportedly infringing disintegrating agent:
“Even if plaintiffs could convincingly show that lactose caused the disintegration of StarLac, the patentee’s disavowal of lactose in order to distinguish [the prior art] during prosecution clearly shows that lactose cannot be a disintegrating agent within the meaning of the [patent-in-suit].”
The smoking gun evidence? “[During prosecution,] [t]he patentee chose to distinguish its invention from [the prior art] by arguing that the reference failed to teach ‘disintegrating agents . . . . Therefore, if lactose is not a disintegrating agent with respect to the [prior art], it would be improper to characterize it as such in the ANDA products.”
Delaware IP Law Blog 