Patent-Term Relief in Korea and the United States: Distinguishing Patent-Office Delay from Regulatory Delay

Executive Summary: This article explains that patent-term relief in Korea and the United States should be analyzed by the legal source of the lost time, not by the shared shorthand of “extension.” In the United States, patent term adjustment compensates for patent-office delay under 35 U.S.C. § 154, while patent term extension compensates for regulatory-review delay under 35 U.S.C. § 156. Korea has comparable but distinct regimes: Article 92-2 addresses delayed patent registration, and Article 89 addresses delay caused by the need to obtain regulatory approval for certain products, especially new-substance medicines and qualifying pesticides. The article emphasizes that these regimes differ in eligibility, calculation, filing deadlines, patent-selection rules, and the scope of enforceable rights during the added term. Its central practical warning is that cross-border counsel must not assume that U.S. PTA/PTE concepts map neatly onto Korean law; instead, they must identify the statutory basis for each added day, docket the correct triggering event, apply the jurisdiction-specific calculation rules, and determine whether the extended right preserves ordinary claim scope or is limited to an approved product or use.

I. Introduction

Cross-border patent-term reviews often begin with a translation problem. U.S. counsel hear "extension" and think of 35 U.S.C. § 156. Korean counsel may use that same English word for both of Korea's term-restoration mechanisms. The shorthand is harmless only until advice turns on it. Misclassification can lead counsel to miss a Korean filing deadline, calculate the wrong period, select the wrong patent for regulatory extension, or overstate the rights that remain enforceable after the ordinary term expires.

The comparative point is not merely terminological: in both systems, the source of the lost term determines eligibility, calculation, filing procedure, and the enforceable scope of the patent during the added period.

The Federal Circuit's decision in In re Cellect, LLC is useful here for its method, not because this article is about obviousness-type double patenting. The court rejected an effort to treat PTA and PTE alike simply because both restore time lost to governmental delay, calling that approach an "unjustified attempt to force disparate statutes into one." In re Cellect, LLC, 81 F.4th 1216, 1226-27 (Fed. Cir. 2023), cert. denied, 145 S. Ct. 153 (2024). Its analysis began with statutory architecture: § 154 and § 156 address different events and impose different limitations. Id. at 1226-28. That is also the right method for comparing U.S. and Korean law.

Korean law uses the language of "extension" for both regimes. Article 89 of the Korean Patent Act addresses extension based on regulatory authorization or registration (허가등에 따른 특허권의 존속기간의 연장). Article 92-2 addresses extension based on delayed patent registration (등록지연에 따른 특허권의 존속기간의 연장). Patent Act, Act No. 950, Dec. 31, 1961, amended by Act No. 21,134, Nov. 11, 2025, arts. 89, 92-2 (S. Kor.) [hereinafter Korean Patent Act]. Calling the first "Korean PTE" and the second "Korean PTA" is convenient. It is also safe only if the analogy does not displace the Korean statutory text.

II. The U.S. Reference Point: Statutory Architecture, Not Labels

A. PTA Under § 154(b)

PTA is tied to examination of a particular U.S. patent application. Section 154(b) awards days for specified USPTO response failures, pendency beyond three years, and certain delays associated with derivation proceedings, secrecy orders, and successful appellate review. Overlapping periods are not double-counted, and applicant delay reduces the award. 35 U.S.C. § 154(b)(1)-(2).

The procedure is integrated into issuance. The USPTO calculates PTA and transmits its determination no later than the patent's issue date; the applicant may then request reconsideration. Id. § 154(b)(3)(B). The practical burden on U.S. counsel is to audit the Office's calculation, not to identify and file an initial post-issuance restoration application.

The text also shows why PTA is its own statutory regime. Section 154(b)(2)(B), for example, expressly prevents PTA from extending a patent beyond a disclaimed date. Cellect treated that choice as evidence that Congress did not intend PTA and PTE to operate identically. 81 F.4th at 1226-28. Whatever the downstream doctrinal context, the interpretive lesson is straightforward: the fact that two statutes add days does not make their added days legally interchangeable.

B. PTE Under § 156

PTE is organized around an approved product and its regulatory history. A patent may qualify if it claims an eligible product, a method of using the product, or a method of manufacturing it; the product has undergone a qualifying regulatory-review period; and the remaining statutory conditions are met. Covered subject matter includes drug and biological products, medical devices, food additives, and color additives. 35 U.S.C. § 156(a), (f)-(g).

The extension is not simply the elapsed review period. Section 156 deducts periods in which the applicant failed to act with due diligence and generally credits only one-half of specified testing periods. PTE may not exceed five years, and the combined post-approval term generally may not exceed fourteen years. Only one patent may be extended for the same regulatory-review period for a product. Id. § 156(c)(1)-(4), (g)(6).

The filing and effect provisions reinforce the product-specific design. A conventional PTE application ordinarily must be filed within sixty days after permission for commercial marketing or use. Id. § 156(d)(1). The extension runs from the patent's original expiration date, expressly including any PTA, and the rights during the extended period are limited by claim type and the approved product or use. Id. § 156(a)-(b). Section 156 is therefore not a second route to PTA; it is a separate bargain tied to a particular regulatory approval.

III. Korea's Regulatory-Approval Extension: The PTE Analogue

A. Article 89 Is Broad; the Enforcement Decree Does the Gatekeeping

Article 89 permits extension when practicing the patented invention requires authorization, approval, registration, or a comparable governmental act under another law, and obtaining that act takes substantial time because efficacy, safety, or similar testing is required. The compensable period is the period during which the invention could not be practiced, excluding delay attributable to the approval holder. Korean Patent Act art. 89(1)-(2).

Read alone, Article 89 sounds capacious. In practice, the Enforcement Decree supplies the decisive eligibility filter. It principally covers:

• first-approved medicines manufactured using a "new substance" as an active ingredient, including specified narcotic and psychotropic medicines; and

• first-registered pesticides or pesticide technical ingredients manufactured using a new substance.

The decree defines a new substance by reference to novelty in the chemical structure of the pharmacologically active portion. Enforcement Decree of the Patent Act, Presidential Decree No. 35,809, Oct. 1, 2025, art. 7(1) (S. Kor.) [hereinafter Korean Patent Act Enforcement Decree].

That narrower delegated definition is where a U.S.-to-Korea comparison most often breaks down. Current Korean law has no direct analogue to § 156's express treatment of medical devices, food additives, or color additives. A favorable U.S. PTE eligibility analysis is therefore only a question-generator for Korea, not an answer.

B. Calculation and the 2025 Portfolio Election

Korea starts with the qualifying period in which the invention could not be practiced and deducts delay attributable to the approval holder. The Act allows one regulatory extension, capped at five years. Korean Patent Act art. 89(1)-(2). That calculation is not the multiphase formula used in § 156, even though the two systems now share similar outer limits.

Amendments effective July 22, 2025 added a fourteen-year post-approval ceiling. The extended expiration date may not fall more than fourteen years after the relevant approval. Korean Patent Act art. 89(1); Act No. 20,700, Jan. 21, 2025, art. 89 & supp. provs. arts. 1-2 (S. Kor.). The five-year maximum and fourteen-year ceiling operate independently; the shorter period controls.

The same amendments changed patent selection from an arithmetic exercise into a portfolio election. If two or more patents relate to the same approval, the applicant must select one for extension. If applications for multiple patents remain pending on that approval, no patent may be extended. Korean Patent Act art. 90(7). An application that is abandoned, invalidated, withdrawn, or finally rejected is treated as though it had not been filed for this purpose. Id. art. 90(8).

The new rules apply to extension applications based on approvals obtained after July 22, 2025. Act No. 20,700, supp. provs. arts. 1-2 (S. Kor.). The approval date thus controls the transition analysis. For covered approvals, counsel should decide which patent to extend before filing, not use parallel applications as placeholders and sort out the portfolio later.

The best candidate is not necessarily the patent that yields the largest nominal number of days. Selection should account for claim coverage of the approved product and use, validity risk, the remaining unextended term, any Article 92-2 extension already obtained, the fourteen-year ceiling, likely generic design-arounds, and the narrower effect of the right under Article 95.

C. Filing Procedure: The Deadline Is Part of the Right

An Article 89 application must be filed within three months after the qualifying approval and may not be filed after the patent enters the final six months of its existing term. The application must identify the patent and claims, the requested period, the approval relied upon, and the supporting grounds and evidence. All co-owners must apply jointly. Korean Patent Act art. 90(1)-(3).

These are not administrative details that can be harmonized with a U.S. filing calendar. The Korean window is three months rather than the ordinary sixty-day period under § 156(d)(1), and Korea adds a final-six-month bar. A cross-border process that waits for completion of the U.S. PTE analysis before opening the Korean file is badly sequenced.

D. Article 95 and the Commercial Meaning of Solifenacin

Article 95 limits the effect of the extended Korean right to practicing the patented invention with respect to the object covered by the approval. If the approval specifies a use, the extended right is limited to that object for the approved use. Korean Patent Act art. 95. The claims themselves are not rewritten; rather, the legal effect of the patent is narrowed during the added period.

A literal reading of "the object" might suggest an exact match to the approved regulatory item. The Korean Supreme Court rejected that formalism in the solifenacin case. The approved product used solifenacin succinate, while the accused product used solifenacin fumarate. The Court held that the accused product could fall within the extended right where a skilled person could readily select the substitute salt and the active ingredient, therapeutic effect, and use were substantially the same. Supreme Court [S. Ct.], Jan. 17, 2019, 2017Da245798 (S. Kor.).

The decision is commercially important because it preserves meaningful blocking value against at least some salt-switch strategies. It is equally important not to overread. Solifenacin does not restore the patent's full ordinary claim scope during the extended term; it gives Article 95 a functional, rather than paperwork-bound, reach. The correct analysis is Korean: whether the accused product remains sufficiently connected to the approved object and use under the factors identified by the Court. U.S. "approved product" concepts under § 156 should not be imported as a substitute.

IV. Korea's Delayed-Registration Extension: The PTA Analogue

The Article 92-2 regime is less exotic doctrinally than regulatory extension, but it is often more dangerous operationally. U.S. systems are accustomed to the USPTO supplying a PTA number at issuance. Korea requires the patentee to recognize the entitlement and act on it.

A. The Four-Year/Three-Year Backstop

Article 92-2 permits an extension when establishment registration occurs later than the later of:

• four years from the patent application's filing date; or

• three years from the request for examination.

The potentially compensable period begins after that later date. Korean Patent Act art. 92-2(1).

This is a back-end pendency test, not a Korean reproduction of the U.S. A-, B-, and C-delay categories. Korean law does not award separate days for each missed office-action, response, issue, secrecy-order, or appellate benchmark. A prosecution history can therefore produce relief in one country and none in the other without inconsistency; the statutes are asking different questions.

Article 92-2 contains no fixed five-year or fourteen-year cap. The extension corresponds to the qualifying delay after deduction of applicant-attributable periods. Id. art. 92-2(1)-(3).

B. Applicant Delay and Family-Specific Clocks

Periods attributable to the applicant are excluded, and overlapping applicant-delay periods may not be deducted beyond the actual applicant-caused delay. Id. art. 92-2(2). The Enforcement Decree identifies the excluded periods, including applicant-requested extensions, delayed or defective procedural acts, certain response periods and late submissions, interruptions and appeals, and delay in paying the patent fee after a patent decision. Korean Patent Act Enforcement Decree art. 7-2. The U.S. rules under § 154(b)(2)(C) are not a proxy for that list.

The filing-date rules also defeat a common family-level shortcut. For a divisional application, the date used for the four-year calculation is the date on which the divisional itself was filed, even though the divisional may receive the parent's filing date for other substantive purposes. Separate rules apply to converted applications and specified PCT-derived applications. Korean Patent Act art. 92-2(4).

For portfolio management, that is not a technical footnote. Each Korean family member needs its own Article 92-2 clock. A docket that stores only the earliest family filing date cannot reliably identify the extension entitlement.

C. The Patentee Must Apply

The patent owner must file a separate extension-registration application within three months after establishment registration. The application must state the requested period and supporting grounds, and all co-owners must apply jointly. Korean Patent Act art. 92-3(1)-(3).

This is the most consequential workflow difference from ordinary U.S. PTA practice. Section 154(b)(3)(B) requires the USPTO to make and communicate the initial determination by issuance, subject to reconsideration. Korea places the first move on the patentee. Registration should therefore trigger an immediate calculation, applicant-delay review, and filing decision even when the patent has no connection to a regulated product.

D. Effect of the Extension

Article 95's product-and-use limitation is expressly tied to regulatory extensions pursued under Article 90. It does not apply to delayed-registration extensions under Articles 92-2 through 92-5. Compare Korean Patent Act arts. 92-2 to 92-5, with id. art. 95.

On the text of the Act, an Article 92-2 extension carries the patent's ordinary claim scope forward to the adjusted expiration date. That feature, more than the Korean use of the word "extension," is what makes Article 92-2 the functional analogue to U.S. PTA.

V. How the Two Korean Regimes Interlock

Korean law expressly contemplates that one patent may receive both forms of relief. If a delayed-registration extension has been registered under Article 92-5, Article 89 uses that extended date as the base from which a regulatory extension is added, subject to Article 89's five-year maximum and fourteen-year post-approval ceiling. Korean Patent Act art. 89(1). Section 156(a) uses the same sequencing concept by defining the U.S. expiration date for PTE to include any PTA under § 154(b).

The practical record should therefore show more than a single "extended expiration date." It should identify the base term, any Article 92-2 extension, any Article 89 extension, the approval supporting the latter, and the Article 95 scope limitation. Without those fields, a date may be numerically correct and legally misleading.

VI. Comparative Summary

Table 1. Relief for Patent-Office Delay

Issue	United States: PTA	Korea: Delayed-Registration Extension
Statutory basis	35 U.S.C. § 154(b)	Korean Patent Act arts. 92-2 to 92-5
Trigger	Qualifying USPTO prosecution delay	Registration after the later of four years from filing or three years from the examination request
Calculation	Statutory delay categories, reduced for overlap and applicant delay	Delay after the four-year/three-year threshold, reduced for applicant-attributable periods
Initial procedure	USPTO determines PTA by issuance	Patentee must file a separate application
Principal deadline	Reconsideration after the USPTO determination	Three months after establishment registration
Fixed cap	No general fixed cap	No stated fixed cap
Effect during added term	Ordinary claim scope	Ordinary claim scope
Primary practice risk	Failure to audit the USPTO calculation	Assuming relief is automatic or using one family-level clock

See 35 U.S.C. § 154(b); Korean Patent Act arts. 92-2 to 92-5.

Table 2. Relief for Regulatory Delay

Issue	United States: PTE	Korea: Regulatory Extension
Statutory basis	35 U.S.C. § 156	Korean Patent Act arts. 89-92, 95
Eligible subject matter	Statutorily defined drug and biological products, medical devices, food additives, color additives, and related methods	New-substance medicines, including specified narcotic or psychotropic medicines, and qualifying pesticides or pesticide technical ingredients, as defined by decree
Compensable period	Statutory regulatory-review period, subject to due-diligence and testing-period rules	Period during which the invention could not be practiced, excluding delay attributable to the approval holder
Maximum term	Five years; generally subject to a fourteen-year post-approval ceiling	Five years; subject to a fourteen-year post-approval ceiling under current rules
Patent selection	One patent per regulatory-review period for a product	One patent per approval under current rules
Principal filing deadline	Ordinarily sixty days after approval	Three months after approval; no filing after entry into the final six months of the existing term
Effect during added term	Limited under § 156(b) by claim type and approved product or use	Limited under Article 95 to the approved object and, where applicable, its approved use, as interpreted under Korean law
Relationship to office-delay relief	Runs from the expiration date including PTA	Runs from the expiration date including any registered Article 92-2 extension
Primary practice risk	Treating the review period as the extension period	Assuming U.S. eligibility carries over or filing before making the one-patent election

See 35 U.S.C. § 156; Korean Patent Act arts. 89-90, 95; Korean Patent Act Enforcement Decree art. 7.

VII. Conclusion

U.S. terminology is useful only if it preserves, rather than erases, the statutory differences. Article 89 can sensibly be called the Korean PTE analogue, and Article 92-2 the Korean PTA analogue. But advice should be keyed to the Korean articles, not to the borrowed labels.

The discipline is simple: identify the legal source of every added day, docket the event that starts the filing period, calculate under the correct jurisdiction's rules, and state whether ordinary claim scope or an approval-limited right survives during the added term. That approach is less elegant than a single category called "patent-term extension." It is also the approach least likely to produce an avoidable error.