MPEP 2138.03
"By Another Who Has Not Abandoned, Suppressed, or Concealed It"

Ninth Edition of the MPEP, Revision 07.2022, Last Revised in February 2023

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2138.03    "By Another Who Has Not Abandoned, Suppressed, or Concealed It" [R-10.2019]

[Editor Note: This MPEP section has limited applicability to applications subject to examination under the first inventor to file (FITF) provisions of the AIA as set forth in 35 U.S.C. 100 (note). See MPEP § 2159 et seq. to determine whether an application is subject to examination under the FITF provisions, MPEP § 2159.03 for the conditions under which this section applies to an AIA application, and MPEP § 2150 et seq. for examination of applications subject to those provisions.]

Pre-AIA 35 U.S.C. 102(g) generally makes available as prior art within the meaning of 35 U.S.C. 103, the prior invention of another who has not abandoned, suppressed or concealed it. In re Bass, 474 F.2d 1276, 177 USPQ 178 (CCPA 1973); In re Suska, 589 F.2d 527, 200 USPQ 497 (CCPA 1979) (The result of applying the suppression and concealment doctrine is that the inventor who did not conceal (but was the de facto last inventor) is treated legally as the first to invent, while the de facto first inventor who suppressed or concealed is treated as a later inventor. The de facto first inventor, by his suppression and concealment, lost the right to rely on his actual date of invention not only for priority purposes, but also for purposes of avoiding the invention of the counts as prior art.).

"The courts have consistently held that an invention, though completed, is deemed abandoned, suppressed, or concealed if, within a reasonable time after completion, no steps are taken to make the invention publicly known. Thus failure to file a patent application; to describe the invention in a publicly disseminated document; or to use the invention publicly, have been held to constitute abandonment, suppression, or concealment." Correge v. Murphy, 705 F.2d 1326, 1330, 217 USPQ 753, 756 (Fed. Cir. 1983) (quoting International Glass Co. v. United States, 408 F.2d 395, 403, 159 USPQ 434, 441 (Ct. Cl. 1968)). In Correge, an invention was actually reduced to practice, 7 months later there was a public disclosure of the invention, and 8 months thereafter a patent application was filed. The court held filing a patent application within 1 year of a public disclosure is not an unreasonable delay, therefore reasonable diligence must only be shown between the date of the actual reduction to practice and the public disclosure to avoid the inference of abandonment.


Once an invention is actually reduced to practice an inventor need not rush to file a patent application. Shindelar v. Holdeman, 628 F.2d 1337, 1341, 207 USPQ 112, 116 (CCPA 1980). The length of time taken to file a patent application after an actual reduction to practice is generally of no consequence except in an interference proceeding. Paulik v. Rizkalla, 760 F.2d 1270, 1271, 226 USPQ 225, 226 (Fed. Cir. 1985) (suppression or concealment may be deliberate or may arise due to an inference from a "too long" delay in filing a patent application). Peeler v. Miller, 535 F.2d 647, 656, 190 USPQ 117,124 (CCPA 1976) ("mere delay, without more, is not sufficient to establish suppression or concealment." "What we are deciding here is that Monsanto’s delay is not ‘merely delay’ and that Monsanto's justification for the delay is inadequate to overcome the inference of suppression created by the excessive delay." The word "mere" does not imply a total absence of a limit on the duration of delay. Whether any delay is "mere" is decided only on a case-by-case basis.).

Where a junior party in an interference relies upon an actual reduction to practice to demonstrate first inventorship, and where the hiatus in time between the date for the junior party's asserted reduction to practice and the filing of its application is unreasonably long, the hiatus may give rise to an inference that the junior party in fact suppressed or concealed the invention and the junior party will not be allowed to rely upon the earlier actual reduction to practice. Young v. Dworkin, 489 F.2d 1277, 1280 n.3, 180 USPQ 388, 391 n.3 (CCPA 1974) (suppression and concealment issues are to be addressed on a case-by-case basis).


Suppression or concealment need not be attributed to the inventor. Peeler v. Miller, 535 F.2d 647, 653-54, 190 USPQ 117, 122 (CCPA 1976) ("four year delay from the time an inventor … completes his work … and the time his assignee-employer files a patent application is, prima facie, unreasonably long in an interference with a party who filed first"); Shindelar v. Holdeman, 628 F.2d 1337, 1341-42, 207 USPQ 112, 116-17 (CCPA 1980) (A patent attorney’s workload will not preclude a holding of an unreasonable delay— the court identified that a total of 3 months was possibly excusable in regard to the filing of an application.).


Notwithstanding an inference of suppression or concealment due to time(s) of inactivity after reduction to practice, the senior party may still prevail if the senior party shows renewed activity on the invention that is just prior to the junior party’s entry into field coupled with the diligent filing of an application. Lutzker v. Plet, 843 F.2d 1364, 1367-69, 6 USPQ2d 1370, 1371-72 (Fed. Cir. 1988) (activities directed towards commercialization not sufficient to rebut inference); Holmwood v. Cherpeck, 2 USPQ2d 1942, 1945 (Bd. Pat. App. & Inter. 1986) (the inference of suppression or concealment may be rebutted by showing activity directed to perfecting the invention, preparing the application, or preparing other compounds within the scope of the generic invention); Engelhardt v. Judd, 369 F.2d 408, 411, 151 USPQ 732, 735 (CCPA 1966) ("We recognize that an inventor of a new series of compounds should not be forced to file applications piecemeal on each new member as it is synthesized, identified and tested for utility. A reasonable amount of time should be allowed for completion of the research project on the whole series of new compounds, and a further reasonable time period should then be allowed for drafting and filing the patent application(s) thereon."); Bogoslowsky v. Huse, 142 F.2d 75, 77, 61 USPQ 349, 351 (CCPA 1944) (The doctrine of suppression and concealment is not applicable to conception without an actual reduction to practice.).


A finding of suppression or concealment may not amount to a finding of abandonment wherein a right to a patent is lost. Steierman v. Connelly, 197 USPQ 288, 289 (Comm'r Pat. 1976); Correge v. Murphy, 705 F.2d 1326, 1329, 217 USPQ 753, 755 (Fed. Cir. 1983) (an invention cannot be abandoned until it is first reduced to practice).