Opening the Prosecution History’s Black Box

By Bernard Chao1

In its recent “Request for Comments on Enhancing Patent Quality,” the Patent Office specifically asked for proposals targeted at clarifying the public record. This paper responds to that request by following up on a recommendation that I made in the Patently-O Blog last year. 2 Specifically, I suggested that it is now time for the Patent Office to record the interviews between applicants and examiners. 3 This proposal would render one component of the public record—the prosecution history—more transparent and thereby give the public better notice of a patent’s scope. Moreover, recording interviews should prevent patentees from suggesting a narrow claim scope before the patent office and later asserting an inconsistent, broader claim scope against its competitors.

The prosecution history is the official record of a patent and it serves to memorialize the dialogue between the applicant and the Patent Office. Courts routinely examine a patent’s prosecution history to interpret a patent’s claims and assess whether a patentee is estopped from asserting infringement under the doctrine of equivalents. Thus, a clear prosecution history often sheds light on where the boundaries of a patent’s claims lie.

Because the lion’s share of communications between an applicant and the Patent Office is in writing, those records are relatively trouble-free. However, there is one part of the prosecution history that is often a kind of black box: the examiner interview. Applicants are permitted to have an interview with the examiner. Patent Office rules require that the applicant and examiner summarize the interview. Unfortunately, these summaries typically fail to provide a full description of what was said at the interview. Instead, they merely identify the prior art discussed and parrot the claim language while only providing the thinnest description of the arguments the applicant made. 4 As one commentator noted, “Readers of prosecution histories often follow a trail of correspondence suggesting that the examiner and applicant are hopelessly at odds, only to discover a poorly documented examiner interview immediately followed by a Notice of Allowability.” 5

This unfortunate “black box” harms the public in two ways. First, failing to retain evidence of what arguments the patentee made makes claim construction more difficult. Arguments that distinguish an application’s claims from the prior art can play a key role in defining how far a claim reaches. Such arguments often say both what the claim does and does not cover. However, if these arguments are not found in the prosecution history, courts will not able to use them to delineate the boundaries of the claim. This inevitably leads to less predictable claim interpretation. But perhaps more troubling, patentees are free to advance broad claim interpretations that may be inconsistent with the statements they made during the interview. This may result in unjustified threats or an unfairly broad claim scope.

Second, the failure to know what was said during interviews also makes it more difficult for the courts to correctly apply the doctrine of equivalents. In some cases, a narrowing amendment estops a patentee from asserting infringement under the doctrine of equivalents. However, one way to escape estoppel is for the patentee to show that the reason underlying the amendment bears no more than a tangential relation to the equivalent in question. Recording examiner interviews would undoubtedly provide the best evidence of the rationale underlying an amendment. Presumably, such evidence would limit the range of available arguments to those that were consistent with the interview record. But without that constraint, the parties are free to hypothesize why an amendment was likely made.

Some may question whether meager interview records are a significant problem. For example, after my suggestion was first published in the Patently-O blog, Professor Dennis Crouch examined four interview summaries and characterized them as doing “a very good job of providing information to the world regarding the issues discussed, the conclusion drawn, and the reasoning for those conclusions.” 6 As is often the case, there is a lack of good empirical evidence on this point. But other evidence suggests that there is a real problem. Patent practitioners tout the interview as a way to avoid having your arguments documented. 7 Other attorneys, presumably litigators, have complained about this hole in the record. 8 Finally, there is evidence that improperly documented interviews cause real problems. 9

To put just a bit more flesh on the proposal, I suggest that an audio recording (e.g., an MP3 recording) be made of all examiner interviews and, to the extent feasible, stored in the Patent Application Information Retrieval (PAIR) system. Because most patents are not asserted or litigated, the Patent Office does not need to transcribe all interviews. Interested parties can pay a fee to have the recordings transcribed as the need arises. This simple solution should crack open the frustrating black box of examiner interviews.

  1. Assistant Professor, Sturm College of Law University of Denver.
  2. See Bernard Chao, Making Examiner Interviews Transparent, PATENTLY-O (Apr. 13, 2014), (suggesting the Patent Office should bring transparency to patent examiner interviews by recording them).
  3. The Patent Office previously considered this reform in 1997. See Notice of Public Hearing and Request for Comments on Procedures for Recording Patent Prosecution File Histories, 62 Fed. Reg. 49471 (Sept. 22, 1997).
  4. See Lester Horwitz & Ethan Horwitz, Intellectual Property Counseling & Litigation, § 9.07(6) (2015) (“(T)he examiner will . . . complete an Interview Summary Record Form PTOL-413 . . . It usually includes a brief summary of what was discussed.”).
  5. John R. Thomas, On Preparatory Texts and Proprietary Technologies: The Place of Prosecution Histories in Patent Claim Interpretation, 47 UCLA L. REV. 183, 190 (1999).
  6. Dennis Crouch, Off-the-Record Examination: Is Conventional Wisdom Wrong?, PATENTLY O (Apr. 15, 2014).
  7. Richard V. Burgujian, Esther H. Lim & Ningling Wang, Practical Considerations and Strategies in Prosecuting U.S. Patent Applications, DIGITIMES (June 2010), (discussing how interviews allow the applicant to avoid stating anything in writing that may “later adversely affect the issued patent.”); Jonathan Cutler, Patent Protection Across the Northern Border, 8 No. 6 E-COMMERCE L. REP. 10 (June 2006) (“Examiner interviews provide an excellent way of dealing with sensitive issues without creating a potentially harmful written record.”); Horwitz & Horwitz, supra note 4 (“(An) advantage of examiner interviews is that they usually produce minimal written record . . . (T)he short summary of the examiner interview summary is unlikely to furnish a basis for file wrapper estoppel arguments.”).
  8. See Hearing Looks at PTO Procedures For Recording Patent Prosecution History, 55 PATENT TRADEMARK & COPYRIGHT J. (BNA) 62, 63 (Nov. 20, 1997) (reporting on complaints about the “hole” in the prosecution record).
  9. See, e.g., Unique Concepts, Inc. v. Brown, 939 F.2d 1558, 1563 (Fed. Cir. 1991) (different judges could not agree about the reason for amendment because “(t)he record contains no indication of what transpired in the interview . . .”); Pure Choice, Inc. v. Honeywell Int’l, Inc., No. 2:06-CV-244, 2008 WL 190317, at *7 (E.D. Tex. Jan. 22, 2008) (finding a claim term incapable of construction where the patentee failed to reduce two phone interviews to a written statement during ex parte reexamination).