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Calculating Patent Term Adjustment: Part 2

This article is second in a series focusing on various issues related to Patent Term Adjustment for U.S. patent applications.  While Part 1 is a general overview of how to calculate patent term adjustment (“PTA”), this article addresses how the filing of various papers during prosecution can affect PTA.  In particular, Requests for Continued Examination (RCEs), terminal disclaimers, and information disclosure statements (IDSs) can all cause adverse PTA effects if not carefully considered.

General Overview

Typically, U.S. patent term is 20 years from the earliest effective filing date, regardless of how long it takes the United States Patent and Trademark Office (“USPTO”) to examine and issue the patent.  In an effort to minimize the possibility of shortened patent term, Congress created the system of PTA, codified at 35 U.S.C. § 154(b), that allows, in certain circumstances, the effective patent term to be extended past 20 years from an application’s earliest effective filing date.  But as with many rules, there are exceptions.

Requests for Continued Examination

As explained in more detail in Part 1 of this blog series, 35 U.S.C. § 154(b)(1)(B) provides a guarantee of no more than a 3-year application pendency (the “3 Year Rule”).  However, an exception to the 3 Year Rule includes time consumed by an RCE.  It has been established that a patent application does not earn a “B” delay from the time an RCE is filed until a Notice of Allowance is issued, unless the USPTO actually resumes examination of the application after allowance.  Additionally, the submission of an RCE after a Notice of Allowance has been mailed will constitute a failure to engage in reasonable efforts to conclude examination, thereby resulting in Applicant delay.  Further discussion of PTA and RCEs can be found at Global IP Matters in relation to the Federal Circuit case Pfizer v. Lee and PTA rules implemented in response to Novartis v. Lee.

Example 1: B delay = 0 Days

filing date, RCE, B CLock

Example 2: B delay = 1 Month

B clock, 1 month, b delay

Example 3: B delay = 3 Months; Applicant Delay = 1 Month

b delay, 3 month, applicant delay, 1 month

Terminal Disclaimers

An applicant may file a terminal disclaimer to overcome a non-statutory double patenting rejection.  The standard USPTO terminal disclaimer form states that the disclaimed patent will not extend beyond the term of the prior patent.  While filing a terminal disclaimer to overcome such a rejection may seem innocuous, terminal disclaimers can nullify potential PTA for the disclaimed patent.  In particular, PTA cannot be used to extend the term of a patent beyond the expiration date set in a filed (and approved) terminal disclaimer.


  • Patent A is filed on January 1, 2000

  • Patent B is a continuation of Patent A

  • Terminal Disclaimer filed in Patent B over Patent A

PTA, variation, patent

Information Disclosure Statements

Inventors and those associated with filing or prosecuting patent applications as defined in 37 CFR § 1.56 have a duty to disclose to the USPTO information that is material to patentability.  This duty is deemed satisfied if such information is submitted to the USPTO via an IDS.  While 37 C.F.R. § 1.97 generally governs when and how IDSs may be submitted at different stages of prosecution, a “timely” filed IDS may not be so timely for purposes of PTA.

As set forth in 37 C.F.R. § 1.704, the filing of an IDS can result in a reduction of the PTA under several circumstances, for example when the IDS is filed after a response to an office action has been filed.  Therefore, the filing of an IDS under certain circumstances can trigger significant PTA reductions under 37 C.F.R. § 1.704.

Example: An RCE was filed on March 24, 2016, and no subsequent action taken by USPTO before the filing of an IDS.  Although the IDS filing is considered “timely” under 37 CFR § 1.97, the IDS filing constitutes a supplemental reply under 37 C.F.R. § 1.704, thereby resulting in an accrual of 364 days of Applicant delay.

RCE, IDS, arrow

The “30-Day Statement” Exception

A reduction of PTA can be avoided for an IDS filing by filing a statement under 37 C.F.R. § 1.704(d), which is provided below with emphasis added.  A statement under 37 C.F.R. § 1.704(d) (the “30-Day Statement”) should not be confused with the certification statements under 37 C.F.R. § 1.97(e).  Unlike the statements under 37 C.F.R. § 1.704(d), the statements under 37 C.F.R. § 1.97(e) have no effect on preventing PTA reduction.

 37 C.F.R. § 1.704(d) states

“A paper containing only an [IDS] … will not be considered a failure to engage in reasonable efforts to conclude prosecution … under paragraphs (c)(6), (c)(8), (c)(9), or (c)(10) of this section … if the paper … is accompanied by a statement that each item of information contained in the [IDS] … (i) Was first cited in any communication from a patent office in a counterpart [1] foreign or international application or [2] from the Office, and this communication was not received by any individual designated in 1.56(c) more than thirty days prior to the filing of the [IDS]…; or (ii) Is a communication that was issued by a [1] patent office in a counterpart foreign or international application or [2] by the Office, and this communication was not received by any individual designated in 1.56(c) more than thirty days prior to the filing of the information disclosure statement.”

Example: An RCE was filed on March 24, 2016, and no subsequent action taken by USPTO before the filing of an IDS with a 30-Day Statement.  Thus, no Applicant delay.

RCE, IDS, 30 day statement


While the above discussion provides a general overview of certain factors that can affect PTA and how it is calculated, patentees are encouraged to consider when and whether to file various papers under every application’s particular circumstances and to verify PTA calculations according to the current rules and regulations of the USPTO.

Part 1

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About this Author

Christina Sperry, Mintz Levin Law Firm, Boston, Medical Tech and Intellectual Property Law Attorney

Christina is an experienced patent attorney whose clients are focused in the medical technology space, from start-ups to large corporations and academic institutions. She advises on patent preparation and prosecution and provides opinions on infringement, validity, and right-to-use for clients in the US and internationally.

The areas of technology in which Christina is particularly focused include mechanical, electrical, and electro-mechanical technical fields such as medical and surgical instruments and devices including endoscopic, soft tissue...

Elissa M. Kingsland, Patent Attorney, Portfolio Management, Boston, Mintz Levin Law FIrm

Elissa is an accomplished attorney experienced in drafting and prosecuting patent applications. She advises clients on the full range of patent portfolio management, from patentability searches and opinions to freedom-to-operate assessments. She has considerable experience in the life sciences, medical technology, and consumer products industries, working on portfolios involving advanced materials, chemistry, and mechanical innovations. 

Prior to joining the firm, Elissa was an associate in the Atlanta office of another international law firm, where she focused on patent prosecution, including post-grant proceedings. Earlier, Elissa served as primary IP counsel for a high tech company in the lighting sector, where she worked with researchers to identify patentable technologies and drafted and prosecuted US patent applications. Before that, she worked as a patent attorney consultant for a medical device company.