Introduction to Interference

by Richard Neifeld, Ph.D, Neifeld IP Law, PC, Arlington VA. (1)

I.      Introduction

Interference law is an area of U.S. patent law with which all patent practitioners should be familiar at least to the extent necessary to provide useful advice. This paper provides an overview of interference law and practice toward that end. In sequence, this paper defines interference, explores the consequences of the holding in Winter v. Fujita including (1) apparent limitation on interference proceedings and (2) how and why to avoid interference proceedings.

II.     Definition of Interference

In this paper, I distinguish between interference and an interference proceeding. Interference is a condition precedent to declaration of an interference proceeding.

Interference is defined by a synthesis of statute, case law, and rule. The relevant statutory section is 35 USC 135(a), which states in pertinent part that:

Whenever an application is made for a patent which, in the opinion of the Director, would interfere with any pending application, or with any unexpired patent, an interference [sic; interference proceeding] may be declared.... [Bold and italics added for emphasis; interpolation supplied.]

Thus, the statute leaves the criteria under which an application and either another application and/or patent interfere to "the opinion of the Director." Those criteria were the subject of the holding in Winter v. Fujita, 53 USPQ2d 1234 (PTOBPAI 1999)(expanded panel consisting of Stoner, Chief APJ, McKelvey, SeniorAPJ, and Schafer, Lee, and Torczon, trial section APJs)(opinion by SAPJ McKelvey), wherein the expanded panel stated that:

      Resolution of an interference-in-fact issue involves a two-way patentability analysis. The claimed invention of Party A is presumed to be prior art vis-a-vis Part B and vice versa. The claimed invention of Party A must anticipate or render obvious the claimed invention of Part B and the claimed invention of Party B must anticipate or render obvious the claimed invention of Party A. When the two-way analysis is applied, then regardless of who ultimately prevails on the issue of priority, the Patent and Trademark Office (PTO) assures itself that it will not issue two patents to the same patentable invention.

The Court of Appeals for the Federal Circuit cited that construction with approval in Noelle v. Lederman, Docket No. 02-1187, 355 F.3d 1343; 2004 U.S. App. LEXIS 774; 69 USPQ2d 1508, (Fed. Cir. January 20, 2004); rehearing en banc denied at 2004 U.S. App. LEXIS 9107 (Fed. Cir. April 9, 2004). As stated in Noelle:

In order for an interference-in-fact to exist, invention A must anticipate or make obvious invention B, and invention B must anticipate or make obvious invention A, thereby meeting both prongs of the 'two-way' test.

On August 12, 2004, the Federal Register published "Rules of Practice Before the Board of Patent Appeals and Interferences, Final Rule". See 69 FR 49960. These rules over haul all practice before the Board, including the rules for interference proceedings. With respect to interference proceedings, these rules specify what constitutes the opinion of the Director within the meaning of 35 USC 135(a) that interference exists. Specifically, new rule 37 CFR 41.203(a) now defines the existence of interference as follows:

(a) Interfering subject matter. An interference exists if the subject matter of a claim of one party would, if prior art, have anticipated or rendered obvious the subject matter of a claim of the opposing party and vice versa.

Thus, the Director has, by rule, memorialized the holding in Winter. What this means is that interference exists only when and between claims of two parties that are either obvious or anticipated in view of each other. Only in instances in which interference exists is the Director authorized to declare an interference proceeding. 35 USC 135(a); 37 CFR 41.203(b).

III. Consequences of Winter

A. Claim Amendments and Antedating May More Often be Employed to Avoid an Interference Proceeding After Winter than Prior to Winter
        To understand the consequences to patent practice in view of Winter, you need to understand how things stood prior to Winter. Prior to Winter, the scope of interference was arguably unclear. Moreover, many members of the interference bar advocated that the Director exercise his discretion specified in 35 USC 135(a) to provide broad subject matter jurisdiction for interference proceedings. Furthermore, and most importantly, many members of the patent bar believed that interference existed whenever a one-ways test was satisfied. In fact, 37 CFR 1.601(n) (2), which has been superceded by 37 CFR 41.203(a), appeared to define interference to require only one-ways obviousness. In fact, in Eli Lilly & Co., v. Board of Regents of the University of Washington,334 F.3d 1264, 1273; 2003 U.S. App. LEXIS 13508; 67 USPQ2d 1161, (Fed. Cir 2003), the dissent argued that the plain meaning of 1.601(n) specified a one-ways obviousness test for interference. (3)
        As a result of the two-ways test requirement of Winter, it is now clear that potential interference proceedings can be avoided under certain circumstances and man be unnecessary from an applicant's perspective. Unnecessary in the sense that the patent applicant can avoid an interference proceeding and still obtain a broad patent. This is because the two-ways test for interference allows the applicant to amend so that the pending claims fail the two-ways test, and also allows the applicant to antedate the 102(e) reference containing the otherwise interfering claims.
        37 CFR 1.131 precludes antedating a U.S. patent reference when the patent reference's claims interfere with the application's claims. (4) Prior to Winter, many believed that a U.S. patent reference could not be antedated when there was one-ways obviousness between the pending claims and the reference patent's claims. However, Winter specified a different conclusion, and its impacts are significant. Thus, removing a limitation in a pending claim previously interfering with a claim in an issued patent may result in that claim no longer satisfying the two-ways test, and therefore no longer interfering. If the applicant can also antedate the U.S. patent reference as to the broader amended pending claim, the broader amended pending claim is not rejectable based upon the existence of the U.S. patent reference.
        For example, assume an application containing (1) a claim to species A and (2) a claim to the genus including species A. The two claims are rejected based upon a patent disclosing and claiming species B, wherein species B is a different species of the same genus. Prior to Winter, most practitioners believed that the applicant could not patent either the claim to species B or the claim to the genus, until after winning an interference proceeding against the reference patent. (5) After Winter, it is clear that the applicant may antedate the reference patent as to the genus claim if the claim to species B (the species claimed in the reference) is not obvious in view of the claimed genus. If the claim to species B is not obvious in view of the genus, that is, if there is no two-ways obviousness, and if the applicant can antedate the filing date of the reference as to the genus, the USPTO has no basis for rejecting the genus claim, and the USPTO should issue the application claiming the genus if the applicant cancels the claim to species A.
        Moreover, if the applicant can show that the claim to species B (the species claimed in the reference) is also non-obvious in view of the claim to species A, and the applicant can antedate species B for its claim to species A, the USPTO also has no basis for maintaining the rejecting of the claim to species A, and the USPTO should issue the application having claims for both species A and the genus. A similar analysis employing the two-ways test applies to claims to combinations of the same sub-combination in diverse applications and patents.
        Therefore, by taking appropriate action, the applicant can minimize the chances of becoming involved in an interference proceeding while still obtaining a useful patent. (6)

B. It is Less Likely that an Interference Proceeding Will be Available for the Purpose of Cancelling Patented Claims After Winter than Prior to Winter

Another consequence of Winter is that it reduces the availability of interference proceedings for the purpose of cancelling claims in an opponent's patent. (7) Just as the two-ways test makes it easier to avoid an interference proceeding, the two-ways test also makes it harder to obtain an interference proceeding. Thus, the holding in Winter limits interference proceedings as a substitute for a generally applicable post-issuance cancellation proceeding. This limitation is one of the factors motivating the industry-wide push for a true post-issuance cancellation proceeding. In fact, interference proceedings were and remain a very imperfect tool for obtaining cancellation of invalid patents for a number of reasons. Those reasons are apparent in view of the discussion below.

IV. Why You Would Want to Avoid an Interference Proceeding

        You would want to avoid an interference proceeding if that was the best course to meet your client's business goals. Why might avoiding an interference proceeding meet your client's business goals? For the following reasons.
        First, avoiding interference by amending claims can result in a patent that protects commercially valuable subject matter. Protecting the commercially valuable subject matter may fully meet your client's business goals.
        Second, the cost of an interference proceeding might exceed the expected benefit of winning the interference proceeding. (8)
        Third, an interference proceeding may substantially delay issuance of any involved application. Depending upon how hard the parties fight, that delay could be up to about 10 years. Keep in mind that, even if you win the USPTO interference proceeding, the USPTO may not promptly issue your involved application. In fact, the USPTO is likely to not issue the patent to the winning party applicant until all judicial review has terminated, (9) and that activity can take the better part of a decade. (10)
         Fourth, to the extent the best prior art against a certain patent is your client's own secret inventive activity, so long as that activity occurred in the United States, that inventive activity would be available under 35 USC 102(g)(2) as prior art in the event that the reference patent is asserted against your client. (11)

V. Conclusion

Our view of the landscape for interference law and practice was fundamentally changed by Winter. Winter tells us that interference only exists when claims meet the two-ways test. As a corollary, amending and antedating may be used to avoid an interference proceeding.

Date/time: November 1, 2004 (10:29am)
C:\Documents and Settings\Owner\Local Settings\Temporary Internet Files\Content.IE5\CHIN0XUN\IntroductionToInterference.wpd

1.        I can be reached via my contact information at:

2.        37 CFR 1.601(n), which has now been superceded, read:

Invention "A" is the same patentable invention as an invention "B" when invention "A" is the same as (35 U.S.C. 102) or is obvious (35 U.S.C. 103) in view of invention "B" assuming invention "B" is prior art with respect to invention "A". Invention "A" is a separate patentable invention with respect to invention "B" when invention "A" is new (35 U.S.C. 102) and non-obvious (35 U.S.C. 103) in view of invention "B" assuming invention "B" is prior art with respect to invention "A".

3.        See Chief Judge Lourie's dissent at 334 F.3d 1264, 1273; 2003 U.S. App. LEXIS 13508, ___; 67 USPQ2d 1161, ___, which reads:

        I believe the Board's action constitutes an abuse of discretion because the language of Rule 601(n) plainly describes a one-way test and does not support a two-way test. While Winter does hold that a two-way test is appropriate, its conclusion, not binding on us, is unsupported by any reasoning. ... [A]nd the majority opinion argue that the PTO's comments in promulgating its interference rules should be considered in our interpretation of the rules, but, when they are contrary to their plain meaning, such comments cannot alter the meaning of the rules.

4.        Old rule 37 CFR 1.131 precluded antedating when the application claimed the same patentable invention specified in old rule 1.601(n). New rule 37 CFR 1.131 as amended by the rules package published in the Federal Register August 12, 2004 precludes antedating when the application claims the same patentable invention specified in 37 CFR 41.203(a), and 37 CFR 41.203(a) specifies the two-ways test.

5.        Cf. Aelony v. Arni, 547 F.2d 566, 570, 192 USPQ 486, 490 (CCPA 1977) and Case v. CPC International, Inc., ___ F.2d ___, ___, 221 USPQ 196, 200 (Fed. Cir. FC 1984)(affirming the practice of phantom counts).

6.        See Neifeld, "Winter, its Impact on Prosecution and Patent Strategy, and Comments on 35 USC 135(b)(2) ," posted at

7.        See Gholz, "Is the Declaration of an Interference a Ticket to Ride to the End of the Line?," posted at

8.        See for example "Patent Interference Costs Statistics" Neifeld, 86 JPTOS 13 (2004) which is also posted on for some information cost of motions in interferences.

9.        See Martin v. Clevenger, 11 USPQ2d 1399, 1400 (Comm'r 1989), n. 1., which reads:

        There are two situations where PTO will not issue a patent to a winning party in an interference. First, if the interference involves a patent and an application, the board holds that the applicant is entitled to prevail, and the patentee seeks judicial review by civil action under 35 U.S.C. 146, a patent is not issued to the winning party. Monsanto Co. v. Kamp, 349 F.2d 389, 146 USPQ 431 (D.C. Cir. 1965). Second, if judicial review is sought in the U.S. Court of Appeals for the Federal Circuit under 35 U.S.C. 141, a patent is not issued to the winning party.

10.        See for example Wu v. Wang, 129 F.3d 1237; 1997 U.S. App. LEXIS 30581; 44 USPQ2d 1641 (Fed. Cir. 1997). The opinion identifies that Wu provoked the interference in its application 07/627,975. USPTO records show that application was filed December 17, 1990, and the opinion indicates that an APJ declared an interference on August 1, 1991, that a final hearing was held in the interference on November 17, 1995, a final judgement issued June 19, 1996, that an appeal to the to the Court of Appeals for the Federal Circuit (CAFC) was filed July 25, 1996, that Wu filed a civil action in the D.C.D.C. September 26, 1996, and dismissing the appeal in favor of the civil action. Subsequently, an appeal from the civil action was had to the CAFC, and a writ of certiari to the Supreme Court denied in 2000; see Wang v. Winner Int'l Royalty Corp., 530 U.S. 1238, 147 L. Ed. 2d 289, 120 S. Ct. 2679, 2000 U.S. LEXIS 4144, 68 U.S.L.W. 3756 (2000).

11. 35 USC 102(g)(2) reads:

... or (2) before such person's invention thereof, the invention was made in this country by another inventor who had not abandoned, suppressed, or concealed it. In determining priority of invention under this subsection, there shall be considered not only the respective dates of conception and reduction to practice of the invention, but also the reasonable diligence of one who was first to conceive and last to reduce to practice, from a time prior to conception by the other. [Subsection (g) amended Nov. 29, 1999, Public Law 106-113, sec. 1000(a)(9), 113 Stat. 1501A-590 (S. 1948 sec. 4806).]