Why a Brief Response is the Best Response to an Office Action

By Rebecca Bachner, Associate

The Federal Circuit recently issued a decision that reminds us of the importance of always remembering prosecution history estoppel when presenting arguments in responses to the USPTO.  Specifically, in Amgen Inc v. Coherus Biosciences Inc., 2018-1993 (Fed. Cir. Jul. 29, 2019)) (“Amgen”), the Federal Circuit highlights how prosecution history estoppel can bar a patent owner from succeeding on its infringement claim under the doctrine of equivalents.

At issue was Amgen’s U.S. Patent No. 8,273,707 which was being asserted against Coherus for infringement.  During prosecution, the USPTO rejected Amgen’s claims as obvious in view of U.S. Patent No. 5,231,178 (“Holtz”).  In response, Amgen presented multiple different arguments.  First, Amgen argued that “the pending claims recite a particular combination of salts. No combinations of salts taught nor suggested in the Holtz et al. patent, nor [are] the particular combinations of salts recited in the pending claims taught nor suggested in this reference.” See Fed. Cir at pgs. 4-5.  Amgen further included a Declaration from the inventor of the ‘707 patent.  “The Declaration did not discuss any salt pairs other than sulfate/citrate, sulfate/acetate, and acetate/citrate—the only claimed pairs in the ’707 patent.”  See Fed. Cir at pg. 5.  The Patent Office issued another rejection and, in a final response, Amgen reiterated that Holtz did not disclose a combination of salts nor did Holtz disclose enhancing the dynamic capacity of an HIC column.  The Amgen patent issued after these arguments were filed.

Amgen filed suit against Coherus alleging infringement of the ‘707 patent under the doctrine of equivalents.  Coherus moved to dismiss Amgen’s complaint under Fed. R. Civ. P. 12(b)(6) stating that Amgen argued that Holtz did not disclose “one of the particular, recited combinations of salts.”  See Fed. Cir at pg. 7.  A magistrate judge issued a report that recommended that Coherus’ motion be granted due to prosecution history estoppel.  The report stated that Amgen “clearly and unmistakably—and indeed, repeatedly—indicated to competitors that it surrendered processes using combinations of salts different from the ‘particular combinations of salts recited in the . . . claims[.]’”  See id.  Therefore, the report found that “prosecution history estoppel bars Amgen from now attempting to reassert surrendered ground involving other combinations of salts.” See id.  The District Court adopted the magistrate judge’s recommendation and granted Coherus’ motion to dismiss.

At the appeal, the Federal Circuit agreed with the lower court’s dismissal.   The Court looked at the prosecution history and noted that “Amgen distinguished Holtz on the basis that Holtz did not teach or suggest the “particular combinations of salts” recited in Amgen’s claims.”   See Fed. Cir at pg. 9.  The Court further noted that “Amgen emphasized “particular” and referred to its particular salts three times in the span of two pages.”  See id.  As to Amgen’s argument that it distinguished from Holtz on the basis of increasing dynamic capacity, the Court states that “while Amgen did assert multiple reasons for why Holtz is distinguishable, our precedent instructs that estoppel can attach to each argument.”  See Fed. Cir at pg. 11.  Importantly, the Court stated that “[t]here is no requirement that argument-based estoppel apply only to arguments made in the most recent submission before allowance.”  See id.

This case is a strong reminder that everything written during prosecution can be used against the patent owner in later litigation.  The fact that “this particular combination” was a non-convincing argument, but still was used against Amgen with doctrine of equivalents shows how careful patent practitioners must be in drafting responses to the USPTO.  Each argument written down is part of the record that can be used against the ultimate patent.  As such, a high emphasis must be placed on having successful interviews with the Examiner.  Examiner interviews should be used at every stage of prosecution.  The Examiner interview is an invaluable way to receive feedback from the Examiner without adding to the written record.  Often, an agreement on claim language can be reached during the Examiner interview.  Based on the agreement, a response can be drafted in a way that minimizes the written record.  As such, Examiner interviews not only help with efficiency but are also a crucial part of obtaining high quality patents.

Getting To Know Your Patent Examiner Through Data

Law360 (June 13, 2019) — How many office actions should I expect at the U.S. Patent and Trademark Office? Should I file a request for continued examination or a notice of appeal? Is it worth filing a pre-appeal?

These, among others, are common questions that practitioners may ask themselves during patent prosecution. In the past, these were mostly questions that could not be answered by taking into account unique proclivities of different examiners. Now, using data analytics, we can get a better sense of how prosecution will go and be able to make an informed decision when a crossroad is reached.

Below, we will explore how to use public data about an examiner, provided by the USPTO, during patent prosecution.

Allowance Rate

By looking at an examiner’s allowance rate (i.e., allowance vs. abandonments), we can get a sense of the journey early on. A high allowance rate is an indicator that the examiner likely has no qualms about allowing applications, and that the examiner likely will not stubbornly stick to poor rejections. For these types of examiners, if appropriate, it may be worth taking a more assertive initial position, including arguing that the rejections should be withdrawn, or offering modest amendments.

However, if the examiner’s allowance rate is low, you may want to consider including substantial amendments or anticipate the possible need to file an appeal as these types of examiners tend to combine three, four, or even five-plus references in their art rejections. If the allowance rate in the art unit is significantly higher than the examiner’s allowance rate, you may want to consider getting the examiner’s supervisor or a primary examiner in the art unit involved early in the process as it may be easier to reach an agreement with them than with the assigned examiner.

Office Actions Per Patent, RCEs Per Patent

A high office action per patent and/or RCE per patent rate may be an indication that reaching allowability will be challenging. These types of examiners also are likely unafraid to combine three, four or five-plus references to make their art rejections. Similar to examiners with low allowance rates, you may want to consider including substantial amendments, getting the supervisory examiner or a primary examiner involved, or planning to file an appeal. You may even want to check the supervisory examiner’s and primary examiner’s allowance rates when deciding whether to get one of them involved.

Interview Statistics

Generally speaking, it is beneficial to interview an examiner as it gives a practitioner an opportunity to get a better sense of the examiner’s interpretations of the application and the applied references, and a chance to explain the invention.

A high interview success rate (i.e. the rate that interviews lead to an allowance in the next office action) may be an indicator that the examiner uses interviews for compact prosecution. These examiners are likely willing to provide suggestions for amendments that would lead to allowance or at least advance prosecution. For these types of examiners, you may want to be prepared to discuss multiple, different types of amendments to take advantage of their willingness to expedite prosecution. However, if the interview success rate is low for the examiner, consider sending a substantive interview agenda with proposed amendments to maximize the chance of reaching an agreement with the examiner.

A comparison of an examiner’s final rejection allowance rate with After Final Consideration Pilot and his/her final rejection allowance rate without AFCP may be an indicator of whether the examiner takes the AFCP program seriously. If there is a significant difference with those rates, the examiner likely uses the allocated two to three hours in the AFCP program to find a way to allow the application. For these types of examiners, consider filing an after-final amendment with an AFCP request before deciding whether to file an RCE or a notice of appeal. However, if the rates are similar, the examiner likely uses pre-pilot procedures regardless of whether an AFCP is filed.

Pre-Appeal Statistics

Pre-appeal statistics can be useful when deciding whether to file an appeal brief or a pre-appeal brief. A high rate of allowance and/or re-opening of prosecution when pre-appeals are filed may indicate that the examiner, the examiner’s SPE, and other panel members in the examiner’s art unit take the pre-appeals process seriously and that it is worth presenting arguments in a pre-appeal brief. However, a low rate of allowance and a low rate of reopening of prosecution after pre-appeal may indicate that it would be better to forego the pre-appeal process and go straight to appeal or go another round with an RCE.

Appeal Statistics

Analyzing an examiner’s appeal statistics may be useful in determining whether to file an appeal or an RCE. If the examiner’s rate of allowance after an appeal is filed is high, it may be worth appealing rather than filing an RCE and avoid narrowing claims unnecessarily. However, if the examiner’s rate of allowance after appeal is low, it is highly likely that your appeal will go to the Patent Trial and Appeal Board.

Since it may take a couple of years for the PTAB to pick up your appeal due to their backlog, you may want to make certain that your client is comfortable with going through with the appeals process and waiting rather than filing an RCE and possibly reaching an agreement with the examiner earlier. For these types of examiners, you may want to consider the examiner’s allowance rate and RCEs per patent rate to help you and your client in making this decision.

If the examiner’s board decision success rate is high, it may be an indication that the examiner goes to the board only when he/she believes that his/her examiner’s answer would be particularly strong. If you receive a compelling examiner’s answer from these types of examiners, consider filing an RCE rather than going to the board.


Just like how data analytics has improved efficiency in other industries, examiner analytics has the potential to improve the efficiency of patent practitioners and patent prosecution. Therefore, using examiner data in your practice may lead to better, quicker and cheaper outcomes for you clients.

By Kris Rhu

The example screenshots in this article are from Patentprufer, which was developed by Harrity & Harrity.