37 C.F.R. § 1.56 ("Rule 56") sets forth the materiality standard. Prior to 1992, the standard was whether a reasonable examiner would have considered the information important in deciding whether to allow the application. Following a 1992 amendment to Rule 56, the standard became whether the information in question establishes a prima facie case of unpatentability or refutes or is inconsistent with an applicant's position supporting patentability.
While the amended standard was not intended to be a significant departure from the original, it plainly defines materiality in narrower terms. Even after the 1992 amendment, the Court of Appeals for the Federal Circuit has always applied the reasonable examiner standard to patents prosecuted under the pre-amendment Rule. See, e.g., GFI, Inc. v. Franklin Corp., 265 F.3d 1268, 1274 (Fed. Cir. 2001). But it has never specifically answered the question of which standard should be applied to patents prosecuted after the Rule's amendment.
The Federal Circuit had a recent opportunity to do so, but opted to leave the question open. In Dayco Products, Inc. v. Total Containment, Inc., 329 F.3d 1358 (Fed. Cir. 2003), the district court had found on summary judgment that the patentee committed inequitable conduct by withholding from the USPTO a co-pending application having substantially similar claims as those of the patent applications at issue, prior art employed to reject the claims in the co-pending application and the rejection itself. Id. at 1362. Each application had been handled by the same prosecuting attorney, but was assigned to a different examiner.
In a case of first impression, the Federal Circuit declined to mandate which standard should apply for patents prosecuted under the 1992 Rule. Instead, the court analyzed the facts against both standards. Applying both standards, it found that the undisclosed application was indeed material, because it could have been the basis of a double patenting rejection; but found that the district court erred by concluding on summary judgment that the prior art met the threshold level of materiality. Id. at 1365-1367. And, because the issues were analyzed under both standards, the question of which standard is proper was side-stepped. The court also held that fact issues existed regarding deceptive intent and the undisclosed prior art's materiality, and consequently vacated and remanded the case. Id. at 1366-1368, 1371.
The Dayco court did, however, address and answer another question of first impression, namely, whether a rejection of substantially similar claims by another examiner in a co-pending U.S. application, is material. As to that issue, and again analyzing it under both standards, the court held that such information was indeed material, and must therefore be disclosed. Id. at 1368.