Inherent Disclosure and Implicit Construction

by Dennis Crouch

Sigray, Inc. v. Carl Zeiss X-Ray Microscopy, Inc., --- F.4th --- (Fed. Cir. 2025)

The Federal Circuit established an important precedent regarding inherent disclosure and implicit claim construction in this IPR appeal, holding that the Board's  purported interpretation of the prior art was rather an implicit claim construction that neither party requested.  The decision, went rely heavily on the Federal Circuit inherency decision in SmithKline Beecham Corp. v. Apotex Corp., 403 F.3d 1331 (Fed. Cir. 2005), allowing for inherency finding even for miniscule or undetectable features found in the prior art.  As I dug into the case though, I was surprised to find that the PTAB did not cite or reference SmithKline, nor did any of the briefs filed in the appeal.  As Judge Dyk wryly stated at oral arguments: "but of course, nobody showed them the SmithKline case." 

This case involved x-ray optics, with claims requiring "magnification of the projection x-ray stage is between 1 and 10 times." Although neither party ever asked for claim construction, the appellate panel went ahead to determine that this claim scope - based upon its "plain meaning" - "includes tiny, even undetectable, magnification" rejecting the PTAB's implicit construction that seemed to require a meaningful divergence from parallel.