The United States, unlike other countries, maintains a patent system in which a patent is intended to be awarded to the first inventor(s) of the claimed invention.  The first inventor, however, is not necessarily the first applicant to file a patent application, nor is he or she necessarily the first inventor(s) to receive a patent.  Occasionally, two or more inventors independently invent the same invention and file separate patent applications directed to such inventions, creating a dilemma for the U.S. Patent and Trademark Office (USPTO), which must determine which inventor(s) is entitled to a patent.[1]  When faced with two pending patent applications that claim the same invention, or when faced with a pending patent application and an issued patent that claim the same invention, the USPTO utilizes an interference proceeding to determine priority of invention.[2]  Thus, interferences are, at their heart, primarily priority contests.[3]  However, the Board of Patent Appeals and Interferences ("the Board"), which adjudicates interferences, may also decide issues of patentability.[4] Consequently, interferences provide a mechanism for challenging patents before the USPTO. 

Corporate competitors have multiple reasons to monitor prosecution of their competitors' pending patent applications, and the possibility of entering into an interference is one such reason.  More specifically, the patent statute creates a time limit for applicants to pursue a patent claim directed to the same or substantially the same invention claimed by another in a published patent application or in an issued U.S. patent.  Applicants who monitor their competitors' patent applications sometimes discover that the applicant may be able to claim in his or her own application the same invention as claimed by the competitor.  In such instances, the applicant may, for strategic reasons, copy the competitor's patent claims and seek to become involved in an interference.  At other times, competitors may fortuitously pursue claims to the same or substantially the same invention, and an interference may be initiated without copying claims.  A patent applicant or patentee who wishes to become involved in an interference may seek to provoke an interference, or the USPTO may sua sponte declare an interference.[5]

Once an interference is declared, the case moves rapidly, because interferences are designed to be concluded within two years.  Interferences are divided into two phases, each of which culminates in an oral argument before a three-judge panel of the Board.  The first phase is is the motions phase and the second phase is the priority phase. One of the three judges presides over the case throughout its pendency before the Board, and an entire interference is considered to be a "trial."  In the first phase, the scope of the dispute is defined and may be redefined.  The Board identifies the invention at issue in the case, and the parties may seek to change the scope of the invention at issue.  Presumptions are established regarding who was first to invent, and such presumptions may be re-established; these presumptions allocate the burden of proof on the ultimate issue of priority during the second phase.  Importantly, competitors may challenge the patentability of each other's claims during the first phase of the interference.  And, as with patent reexaminations, the Board does not presume the validity of the claim(s) of an issued patent that is involved in an interference.  In the second phase of an interference, the Board determines which party was first to invent the invention, e.g., by considering proofs of conception and efforts to reduce the invention to practice.  In practice, however, many cases do not proceed to the second phase, but rather are resolved or are settled by the end of the first phase. 

Patentability challenges are made by filing one or more motions attacking an opponent's patent (or application) claims on grounds such as lack of enablement, lack of an adequate written description and/or lack of patentability in view of the prior art.  An attack based on prior art can include, for example, an argument that a patent involved in the interference is invalid in view of earlier scientific references and/or an earlier-filed patent application or patent.  Such prior art can even include an earlier-filed patent or application filed by the attacker.  See 35 U.S.C. §102(e).  A patent owner can oppose such a motion by, for example, establishing that the attacker failed to meet its burden of proof, demonstrating that an earlier-filed "prior art" patent application is not entitled to the benefit of its filing date, or proving a date of invention prior to the filing date of the alleged prior art.  One caveat, however, is that a party who attacks its opponent's claims as unpatentable over the prior art must explain why that party's own claims also are not unpatentable over the same art.  At times, an attacker knowingly takes a "scorched earth" approach and lodges arguments that may render its own claims unpatentable, all the while hoping that at least its opponent's claims will go down in flames.  This occurs, for example, when the main goal of the attacker is to deny any patent claims to his or her opponent and thus provide the attacker the ability to commercialize a product and/or operate free from blocking patent claims.[6]

Procedurally, attacks on an opponent's case are made by motions.  Motions in interferences are subject to strict page limits and the movant must prove its case by a preponderance of the evidence.  And, the motions must allege facts that are supported by citations to evidence (e.g., expert declarations, scientific references, the involved patent and/or application(s), etc.).  It is common to submit testimony of one or more experts to substantiate one's arguments, particularly arguments made to establish what a person of ordinary skill in the art would have understood as being in the art or what was common knowledge in the art on the filing date of the patent being attacked.  Direct expert testimony is provided by written affidavit or declaration, and the expert subsequently is invariably subjected to cross-examination by deposition.  Typically, an expert's testimony is later countered by an opposing expert's testimony submitted in support of the opponent's opposition to the attacker's motion.  Additional, but severely limited, evidence can be submitted in support of a reply brief later filed by the movant. 

Although the Federal Rules of Evidence apply in interferences, the Federal Rules of Civil Procedure do not apply, and there are significant distinctions between depositions held in interferences as compared with depositions held in district court litigations.  For example, the proceedings differ with respect to the privileges and objections that can be raised during depositions.  Additionally, depositions in interferences are not merely for unearthing information that later will be used at trial, since the entire interference proceeding is considered to be a trial.  On rare occasions, a judge may participate in a deposition in person or by telephone, but, most commonly, judges in interferences do not hear live testimony of witnesses and depositions are typically not video taped as they are in district court litigation.  Additionally, interferences rarely involve any discovery beyond depositions of witnesses who have submitted affidavits or declarations.  In general, the Board tends to be reticent to grant such additional discovery.  Finally, the oral arguments that conclude each phase of an interference also are streamlined as compared with oral arguments in district court litigation.  Oral arguments in interferences typically last a total of only about one hour and do not involve live testimony.[7]  Rather, such oral arguments provide the judges with a brief opportunity to seek clarity regarding issues that have been raised in the parties' motions, oppositions, and replies.

Because all motions attacking an opponent's patent (or application) typically must be filed simultaneously, with no “second bite at the apple,” a party to an interference must devise a comprehensive strategy for managing and balancing the various arguments the party intends to make regarding its opponent's case — and its own case — for patentability.  For example, such a comprehensive strategy should maintain consistency when characterizing the state of the art when assessing enablement and when considering what would have been obvious to a person of ordinary skill in the art.  It is critical that such a comprehensive strategy be devised early on in the proceeding.  

A party who is dissatisfied with a decision of the Board in an interference can seek judicial review of that decision in U.S. district court, or appeal directly to the United States Court of Appeals for the Federal Circuit (Federal Circuit).  Review in district court offers the advantage that additional evidence frequently can be submitted and additional discovery typically is easier to obtain than during the course of an interference before the Board.  An appeal from the district court action can be taken to the Federal Circuit. 

The availability of interferences as a mechanism to attack patents should not be overlooked.  Of course, such an option is available only to parties who have (or can acquire) a competitive patent or patent application position.  To such parties, however, interferences offer possibilities that do not exist in other proceedings before the USPTO.  For example, a party who attacks a patent by requesting reexamination cannot base such an attack on lack of enablement, lack of written description, or on prior art grounds that do not raise a substantial new question of patentability based on prior art patents or printed publications or declarations against interest.  Additionally, in contrast to patent reexaminations, a settlement in an interference can rapidly lead to a halt of the proceeding, with one party requesting adverse judgment in the proceeding.  By contrast, the USPTO will convert a "settled" inter partes reexamination into an defacto ex parte reexamination (with no interview right) and continue to re-assess the patentability of the claim(s) in reexamination.  One benefit of a "win" in an interference is that it may not only lead to cancellation of the competing patent claims, but it may also create a potentially insurmountable hurdle at the USPTO should the "loser" later pursue similar patent claims.[8] 

Legislation pending before Congress may eventually signal the end to interferences as we know them, by replacing the existing first-to-invent system with a first-inventor-to-file system, and by creating a post-grant review proceeding that will provide a new mechanism for attacking patents before the USPTO.[9]  If such legislation is enacted, post-grant review proceedings as current envisioned will be adjudicated by a Patent Trial and Appeal Board that is formulated by the very judges who comprise the current Board.  Thus, it is likely that the Board's approach in adjudicating interferences will foreshadow its approach in adjudicating any post-grant review proceeding that will be devised, and lessons learned from interferences likely will be of value in post-grant review proceedings.  In the meantime, corporate competitors should not overlook the possibility of using interference proceedings to challenge patents before the USPTO.