The Federal Circuit has denied David Jang’s petition for en banc rehearing in Jang v. Boston Scientific. The basic issue surrounds Boston Scientific’s “ensnarement defense” and whether it had been waived.
The ensnarement doctrine limits the scope of the doctrine of equivalents – barring the patentee from asserting a scope of equivalency that will encompass or “ensnare” the prior art. DePuy Spine, Inc. v. Medtronic Sofamor Danek, Inc., 567 F.3d 1314 (Fed. Cir. 2009). This approach is closely akin to the ordinary claim construction canon of construing terms in order to preserve validity. However, the ensnarement doctrine is actually applied while the construe-to-preserve-validity approach is generally a limited afterthought if even considered.
The doctrine makes perfect sense at this high level – patents should not cover what is found in the prior art. The difficulty comes in the doctrinal and procedural details.
- Who should decide (CAFC: the judge);
- What is the standard (CAFC: it is question of law);
The particular issue in the en banc setup was whether Boston Scientific’s belated raising of the ensnarement doctrine constituted waiver of the doctrine – BSC did not raise the defense in the pretrial order. In its decision, the Federal Circuit ruled that it was not necessary to raise the defense at that point since the District Court had already indicated that the issue would be decided post-trial.