Behind the File Wrapper: Discoverability of Patent-Prosecution Materials: Privilege, Work Product, Patent Agents, Foreign Associates, and Internal Counsel Communications

Executive Summary: Patent-prosecution files are neither categorically privileged nor automatically subject to production; each document requires a forum-specific analysis of its purpose, participants, confidentiality, and relationship to anticipated litigation. Attorney-client privilege protects qualifying confidential communications made to obtain or provide legal advice, while work-product protection generally requires a concrete litigation nexus that routine ex parte prosecution does not supply. Governing law must be identified first because Federal Rule of Evidence 501 may require state privilege law for state-law claims, the Federal Circuit applies its own law to patent-specific privilege questions and regional-circuit law to other issues, and work-product and mixed-purpose standards vary among circuits. In federal patent litigation governed by Federal Circuit law, confidential communications with registered patent agents may receive the limited privilege recognized in Queen’s University when they concern authorized USPTO practice. Internal emails between supervising and junior attorneys likewise may be privileged when they formulate legal advice concerning an office action, but administrative and status-only communications are not protected merely because lawyers exchanged them. Cross-border communications require additional attention to the foreign associate’s professional status, authorized role, governing law, and necessity to the representation; the USPTO’s July 2026 foreign-domicile representation rule changes who must handle U.S. correspondence but does not itself establish privilege. Careful engagement terms, restrained distribution, separation of legal advice from administrative content, and document-specific privilege logs provide the strongest foundation for protecting legitimate prosecution confidences without overstating the applicable doctrines.

I.                   The file wrapper and the “shadow file”

The official patent file tells only part of the prosecution story. Behind the public record may sit invention disclosures, prior-art analyses, drafts and redlines, examiner-interview notes, emails among prosecution counsel, instructions to foreign associates, portfolio recommendations, and communications with patent agents. When validity, infringement, inventorship, ownership, or inequitable conduct later becomes disputed, an adversary may seek that private “shadow file.”

The instinctive response—that the materials belong to counsel and therefore are protected—is too broad. The fact that a document was created during patent prosecution does not determine whether it is privileged or protected as work product—and therefore does not by itself answer whether the document must be produced. Nor does a “Privileged and Confidential” legend, placement in a lawyer’s electronic file, or the presence of an attorney on an email chain. Conversely, the absence of privilege or work-product protection does not itself establish that an item falls within the permissible scope of discovery; relevance, proportionality, other protections, and protective-order terms remain separate questions. Fed. R. Civ. P. 26(b)(1), (c).

Two doctrines dominate the analysis: attorney-client privilege and the work-product doctrine. They often overlap, but they protect different interests and turn on different facts. Attorney-client privilege protects qualifying confidential communications made to obtain or provide legal advice. Work product generally protects documents and tangible things prepared in anticipation of litigation or for trial. A prosecution document may satisfy both doctrines, one doctrine, or neither.

That distinction matters acutely in patent practice. Preparing and prosecuting a patent application is the practice of law. Sperry v. Florida ex rel. Fla. Bar, 373 U.S. 379, 383, 402 (1963). Confidential communications made for that purpose may therefore be privileged. Routine prosecution, however, ordinarily is an ex parte process directed to obtaining a government grant, not litigation against an adversary. Prosecution materials that do not embody a protected communication may consequently fall outside attorney-client privilege without qualifying as work product.

The correct analysis is document specific. It asks who created the material, why it was created, whether and to whom it was communicated, the legal status and role of each participant, whether confidentiality was maintained, and - for work product - whether a concrete anticipated dispute materially influenced its preparation.

II.                Two protections with different foundations

Attorney-client privilege generally protects a confidential communication between a client and an attorney made for the purpose of obtaining or providing legal advice. It is not limited to litigation. Subject to waiver and recognized exceptions, such as crime-fraud, a communication satisfying the doctrine’s elements ordinarily remains protected regardless of an opponent’s need for it.

The privilege protects communications, not underlying facts. Upjohn Co. v. United States, 449 U.S. 383, 395–96 (1981). An inventor therefore may have to testify about conception, testing, prior-art searches, or knowledge of a reference even if those subjects were discussed with prosecution counsel. A recent patent case applied the same distinction to drawings prepared at patent counsel’s alleged direction: neither the drawings themselves nor facts about their creation were privileged merely because counsel was involved. Resh, Inc. v. Conrad, No. 22-cv-01427-EJD (VKD), slip op. at 3–5 (N.D. Cal. Feb. 23, 2024). If otherwise relevant, proportional, and unprotected, underlying facts may be obtained from laboratory notebooks, test data, testimony, emails, or other sources.

A preexisting technical or business record likewise does not become privileged merely because it is sent to a lawyer. Fisher v. United States, 425 U.S. 391, 403–05 (1976). The cover email may be privileged if it reveals a request for legal advice, but the attached record must qualify for protection in its own right.

Work product serves a different purpose. Federal Rule of Civil Procedure 26(b)(3) protects documents and tangible things prepared in anticipation of litigation or for trial by or for a party or its representative. Fed. R. Civ. P. 26(b)(3). The doctrine is not confined to attorney-client communications and may cover investigative material, attorney notes, expert-related material, and work performed by nonlawyer representatives. Conversely, it ordinarily requires a genuine litigation nexus that attorney-client privilege does not.

Ordinary or fact work product does not create an absolute bar to production. Under Rule 26(b)(3), a court may order production if the requesting party shows substantial need and cannot obtain the substantial equivalent without undue hardship. The rule directs courts to protect counsel’s mental impressions, conclusions, opinions, and legal theories more strongly. The threshold question nevertheless comes first: even an attorney’s candid mental impressions are not work product unless the material was prepared in anticipation of litigation under the governing forum’s test.

Feature	Attorney-client or patent-agent privilege	Work-product doctrine
Protected interest	Confidential legal consultation	Integrity of litigation preparation
Typical subject	A qualifying communication	A document or tangible thing prepared in anticipation of litigation or for trial
Litigation required?	No	Generally yes
Routine prosecution	Frequently can support privilege	Ordinarily does not support work product
Can need overcome it?	Generally no, absent waiver or an exception	Sometimes for fact work product; opinion work product receives greater protection

The distinction creates a recurring prosecution gap. A lawyer’s uncommunicated analysis is not automatically an attorney-client communication. If it was created only for routine prosecution and lacks the litigation nexus required under the governing test, it may fail the work-product test as well. That gap makes purpose, communication, and documentation more important than labels.

III.             Governing law comes first

Applicable law is a threshold question. Federal Rule of Evidence 501 makes federal common law—developed by federal courts in the light of reason and experience—the ordinary source of privilege law in federal-question litigation. But the rule adds an important qualification: in a civil case, state law governs privilege regarding a claim or defense for which state law supplies the rule of decision. Fed. R. Evid. 501. A federal patent case therefore may implicate federal privilege law for the patent claims yet require attention to state privilege law for a state-law ownership, contract, malpractice, or fiduciary-duty claim. The analysis should identify the claim or defense to which each withheld communication relates; the presence of a patent somewhere in the dispute does not select one body of privilege law for every document.

Federal patent cases add a second choice-of-law layer. When reviewing a district court, the Federal Circuit ordinarily applies regional-circuit law to non-patent issues but applies its own law to substantive patent questions and procedural questions sufficiently bound up with enforcement of the patent right. In re Queen’s Univ. at Kingston, 820 F.3d 1287, 1290–91 (Fed. Cir. 2016); In re Spalding Sports Worldwide, Inc., 203 F.3d 800, 803–04 (Fed. Cir. 2000). Spalding illustrates the dividing line. The court applied Federal Circuit law because privilege for an invention record submitted for patent evaluation implicated substantive patent law. 203 F.3d at 803–04. By contrast, it explained that In re Regents of Univ. of Cal. had properly applied Seventh Circuit law to a licensor-licensee common-interest question because that issue was not unique to patent law. Id. at 804 (discussing 101 F.3d 1386, 1390 n.2 (Fed. Cir. 1996)). Patent-specific questions concerning invention disclosures, prosecution communications, or patent-agent privilege may therefore be governed by Federal Circuit law, while a non-patent-specific issue may be governed by the regional circuit.

Work product requires a separate choice-of-law check. Rule 501 addresses privileges; in federal discovery, the work-product protection for documents and tangible things prepared in anticipation of litigation is principally stated in Federal Rule of Civil Procedure 26(b)(3). Fed. R. Civ. P. 26(b)(3)(A). Regional circuits do not use identical formulations for dual-purpose materials. The Second Circuit asks whether a document was created because of anticipated litigation and whether it would have been prepared in essentially similar form without that prospect, while the Fifth Circuit asks whether the primary motivating purpose of its creation was to aid possible future litigation. Compare United States v. Adlman, 134 F.3d 1194, 1202 (2d Cir. 1998), with United States v. El Paso Co., 682 F.2d 530, 542–43 (5th Cir. 1982). Standards for mixed legal and nonlegal communications also vary: the Second Circuit asks whether legal advice was the communication’s predominant purpose, whereas the D.C. Circuit asks whether obtaining or providing legal advice was one of its significant purposes. Compare In re County of Erie, 473 F.3d 413, 420 (2d Cir. 2007), with Fed. Trade Comm’n v. Boehringer Ingelheim Pharms., Inc., 892 F.3d 1264, 1267–68 (D.C. Cir. 2018).

The document-specific inquiry should therefore begin by identifying the court, the claims and defenses to which the document relates, the federal or state source of privilege law, whether Federal Circuit or regional-circuit doctrine governs the particular issue, and the forum’s test for work product or a mixed-purpose communication. Only then should the analysis turn to whether the document satisfies the elements of the asserted protection.

IV.            Attorney-client privilege in ordinary U.S. prosecution

The Federal Circuit’s leading prosecution-privilege decision is In re Spalding Sports Worldwide, Inc., 203 F.3d 800, 805–07 (Fed. Cir. 2000). There, inventors submitted an invention record to their company’s legal department. The record described the invention, identified potentially relevant prior art, and provided information bearing on patentability. The court held it privileged because it was confidentially provided to counsel primarily to obtain legal advice concerning patentability and assistance in preparing a patent application.

Spalding rejected the argument that technical content or prior-art information necessarily converts an invention disclosure into an unprivileged factual report. Looking to the communication’s overall tenor, the court found an express or implied request for legal services. It did not parse the record into protected “legal” sentences and unprotected “technical” sentences. Nor did later public disclosure of some technical content in a patent application retroactively eliminate privilege over the earlier confidential communication.

The decision does not make every invention disclosure, draft application, or prosecution document categorically privileged. The proponent still must establish confidentiality and a legal purpose. An invention form routed simultaneously to counsel, business executives, product managers, and an invention committee for budgeting, compensation, or portfolio ranking may require a different analysis. Dual-purpose communications should be evaluated under the governing forum’s test for mixed-purpose communications.

As a practical matter, confidential communications seeking advice about patentability, inventorship, claim scope, drafting, filing strategy, or a response to the USPTO are strong privilege candidates. Draft exchanges may qualify to the extent they reveal confidential client information, proposed legal advice, or strategic alternatives that were not publicly disclosed. Ordinary research records, raw test data, administrative reports, commercial forecasts, and public prosecution papers do not become privileged merely because counsel reviewed them.

Corporate representation adds another layer. Communications from inventors and other employees may be privileged when made within their corporate responsibilities so that company counsel can advise the company. Upjohn, 449 U.S. at 394–95. But the corporate privilege belongs to the organization. An inventor interviewed by company counsel is not automatically counsel’s individual client, and the engagement and interview should make that distinction clear.

An inequitable-conduct allegation also does not automatically eliminate privilege. Spalding required a prima facie showing that the communication was made in furtherance of fraud. Merely alleging that a reference was not cited - particularly when the reference was provided to counsel for evaluation - does not itself satisfy the crime-fraud exception.

V.               Patent agents: a distinct privilege tied to authorized practice

Clients often rely on registered patent agents who may practice before the USPTO but are not attorneys. In federal patent litigation governed by Federal Circuit law, In re Queen’s Univ. at Kingston, 820 F.3d 1287, 1290–94, 1301–02 (Fed. Cir. 2016), recognizes a limited federal-common-law patent-agent privilege for qualifying communications within the agent’s authorized USPTO practice. The protection is distinct from, though functionally analogous to, attorney-client privilege. Queen’s University does not itself establish a universally applicable rule for every tribunal or every state-law posture; the governing-law analysis comes first.

Queen’s University held that confidential communications between a client and a nonattorney patent agent are privileged when made in furtherance of tasks authorized by Congress and the USPTO, including services reasonably necessary and incident to those tasks. The party asserting the privilege bears the burden of establishing that the particular communication falls within that authorized scope. 820 F.3d at 1301–02.

The authorized-practice inquiry is functional. Under 37 C.F.R. § 11.5(b)(1), core examples include advice about patentability; preparing, filing, and prosecuting applications; responding to office actions; proposing amendments; and conducting examiner interviews. A communication must concern the agent’s authorized work or a service reasonably necessary and incident to it; the presence of a patent agent does not protect unrelated legal, business, or administrative content.

The privilege does not transform a patent agent into a general legal adviser. Queen’s University identified infringement advice, certain opinions about the validity of another party’s patent in contemplation of litigation or a transaction, and other work outside authorized USPTO practice as beyond the doctrine. Licensing, corporate transactions, district-court litigation strategy, and state-law questions ordinarily require a separate privilege basis.

The protection therefore should be described by function rather than title. A registered patent agent’s email is not privileged simply because it relates to a patent. The proponent must establish confidentiality, a request for or provision of professional advice, and a subject within authorized practice. Nor is attorney supervision a prerequisite to the direct privilege recognized in Queen’s University, although communications among an attorney, patent agent, and their shared client may have overlapping grounds for protection. A recent Delaware decision underscores the pleading and proof point: the court treated the patent-agent privilege as independent from ordinary attorney-client privilege and rejected blanket assertions where the proponent had not invoked the correct privilege or established the practitioners’ qualifications and functions. Chervon (HK) Ltd. v. One World Techs., Inc., No. 19-1293-GBW, slip op. at 3–8 (D. Del. Jan. 13, 2023).

VI.            Internal emails about responding to an office action

A common prosecution workflow creates a deceptively difficult privilege question. A client sends an office action to supervising counsel. The supervising attorney asks a junior associate to analyze the rejections and prepare a response. The associate circulates proposed arguments and amendments, and the supervising attorney revises the draft before seeking client approval. If the patent is later litigated, an accused infringer may request the entire internal email chain.

The client’s absence from those emails does not necessarily defeat privilege. Courts generally recognize that lawyers representing the same client must be able to confer confidentially while providing that client’s legal services. In Natta v. Zletz, 418 F.2d 633, 637 & n.3 (7th Cir. 1969), correspondence between corporate patent counsel and outside patent counsel was protected because the communications were, in substance, part of the corporation’s relationship with its outside lawyers. Richards v. Kallish, No. 22-cv-9095 (CS) (VR), 2023 WL 8111831, at 2, 6–8 (S.D.N.Y. Nov. 22, 2023), likewise treated confidential patent-prosecution communications as privileged and held that including inventors, technical personnel, and prosecution staff did not destroy confidentiality when their participation facilitated the representation. More recently, LKQ Corp. v. Kia Motors America, Inc., No. 21 C 3166, 2023 WL 3200236, at *6–7 (N.D. Ill. May 2, 2023), protected adequately logged emails between a patent-prosecution team and in-house counsel that exchanged information and counsel’s opinion concerning patent-filing strategy.

Hercules Inc. v. Exxon Corp., 434 F. Supp. 136, 146–53 (D. Del. 1977), applied similar reasoning within a patent department. A subordinate patent professional received an assignment to conduct legal research for a supervising attorney’s use in advising the client. The court saw no meaningful difference between that arrangement and an assignment to a junior associate. A recent, non-prosecution decision likewise recognized that internal drafts, attorney revisions, and emails transmitting drafts may remain privileged when confidentially prepared to obtain or communicate legal advice. Burge v. Teva Pharm. Indus. Ltd., No. 22-cv-2501-DDC-TJJ, 2025 WL 2172466, at *12–13 (D. Kan. July 31, 2025).

That reasoning fits the ordinary office-action assignment. A supervisor’s email asking a junior lawyer to determine whether cited references teach a disputed limitation, assess written-description support, evaluate estoppel or disclaimer risks, or recommend whether to argue or amend ordinarily participates in providing legal advice to the client. The associate’s analysis, draft, and redline may likewise be privileged when confidentially created and circulated to formulate or communicate that advice. See LKQ, 2023 WL 3200236, at 6–7; Burge, 2025 WL 2172466, at 12–13. The protection is the client’s attorney-client privilege—not a freestanding privilege belonging to the two lawyers—and the client need not be copied on every step of the drafting process.

The protection is functional, not status based. IQL-Riggig, LLC v. Kingsbridge Techs., No. 19 CV 6155, 2021 WL 1172654, at *3–5 (N.D. Ill. Mar. 29, 2021), declined to treat same-firm attorney emails as privileged merely because they concerned the client’s litigation, although the messages qualified as work product because they addressed defending a counterclaim and summary-judgment motion. In the prosecution setting, Huber Engineered Woods LLC v. Louisiana-Pacific Corp., No. 19-342-GBW-SRF, slip op. at 10–11, ¶¶ 22–24 (D. Del. Sept. 30, 2022), held that attorney-to-attorney emails merely confirming USPTO filing status were not privileged because they disclosed no legal strategy or substantive advice. Thus, filing confirmations, scheduling, signature requests, and bare transmittals remain weaker candidates even when every sender and recipient is a lawyer.

Geomatrix Sys., LLC v. Eljen Corp., No. 3:20-cv-1900, 2022 WL 603029, at *2–3 (D. Conn. Mar. 1, 2022), supplies the corresponding prosecution warning. The court rejected a categorical attempt to withhold prosecution counsel’s internal work papers and required a document-specific showing. Read with Natta, Hercules, LKQ, and Huber, the careful formulation is that confidential legal-team communications are often privileged when they request, transmit, or refine legal advice for the client, or reveal client confidences. Two lawyers on an email, standing alone, are not enough. Regional-circuit differences concerning derivative or inter-attorney privilege make the document’s content and function especially important.

The contrast is practical:

•             “The client instructed us to preserve the system claim. Reference A appears to lack the claimed controller, so I recommend traversing the section 103 rejection, with the attached amendment as a fallback” presents a strong privilege claim. It reveals a client instruction and provides legal analysis for further advice.

•              

•             A supervisor’s response discussing written-description risk and directing a narrower amendment is similarly strong.

•              

•             “Please prepare the response by Friday,” a docket entry, a fee estimate, or a notice that an office action issued may disclose no confidential legal advice.

•              

•             An attorney’s private research notes or uncommunicated assessment of a claim’s weakness may fall outside attorney-client privilege in a forum requiring a protected communication or a demonstrable role in advising the client.

•              

Drafts require their own analysis. An internal draft response or redline may reveal counsel’s legal advice through proposed arguments, rejected amendments, comments about support, and strategic choices. Burge, although not a prosecution case, illustrates the general rule that confidential internal drafts and counsel’s revisions may be privileged when they serve the legal-advice process. 2025 WL 2172466, at *12–13. Once filed, the response has been disclosed to the USPTO and, if and when the application file becomes publicly available, generally becomes public; filing does not itself create privilege in the submitted content. Draft status alone is not dispositive, and the email and each attachment should be reviewed separately. Attaching a public office action, cited patent, raw test result, or preexisting technical record to a privileged email does not transform the attachment into a privileged document.

Work product provides no automatic backstop. Hercules declined work-product protection for draft amendments, draft claims, attorney notes concerning ex parte prosecution, and handwritten notes on an office action when they addressed prosecution rather than a concrete adversarial dispute. 434 F. Supp. at 151–53. Geomatrix likewise rejected the proposition that a general plan to obtain and later assert patents categorically protects prosecution materials. 2022 WL 603029, at *2–3. And Resh found no work product where the record did not show that inventor drawings allegedly prepared at patent counsel’s direction were created in anticipation of litigation. No. 22-cv-01427-EJD (VKD), slip op. at 3–5. The proponent must show that the particular email or draft bears the litigation nexus required under the governing law.

VII.         Foreign associates and cross-border prosecution communications

International prosecution adds a threshold question that domestic prosecution ordinarily does not: who, precisely, is the “foreign associate”? The label may describe a foreign attorney-at-law, a regulated patent practitioner who is not admitted to a general bar, an in-house patent professional, a translator exercising legal or technical judgment, or a filing vendor performing ministerial tasks. Those categories are not interchangeable. In some countries, a person styled a “patent attorney” may practice before a patent office but is not an attorney-at-law. Credentials, authorized functions, and role therefore matter.

A.                 The July 2026 foreign-domicile representation rule

Effective July 20, 2026, the USPTO requires representation by a patent practitioner when at least one identified applicant or patent owner is domiciled outside the United States or its territories; unless otherwise specified, papers submitted on such a party’s behalf must be signed by a patent practitioner. The requirement applies to papers received on or after that date without regard to the application’s filing date. Required Use by Foreign Applicants and Patent Owners of a Patent Practitioner, 91 Fed. Reg. 13,510, 13,512–13, 13,519 (Mar. 20, 2026) (amending 37 C.F.R. §§ 1.9, 1.31–.33; effective July 20, 2026); 37 C.F.R. §§ 1.31(a)(2)–(3), 1.33(b)(3) (2026). The rule materially changes the mechanics of cross-border prosecution, but it does not itself establish privilege. The analysis should separately identify the USPTO practitioner responsible for U.S. correspondence, the foreign lawyer or other practitioner advising on foreign law or foreign prosecution, the client represented by each, and any agency or reasonable-necessity basis for including additional participants in a confidential communication. The proponent must still establish the elements and scope of the asserted privilege under the law governing the forum; registration, representation, and signature authority do not by themselves make every communication in the prosecution chain privileged.

B.                 Choice of law comes first

One frequently used approach, particularly in Second Circuit cases involving foreign privilege, is the “touch-base” test. It asks which country has the predominant or most direct and compelling interest in the confidentiality of the communication. Communications relating to a U.S. proceeding or advice about U.S. law typically touch base with the United States; communications centered on foreign proceedings or foreign law typically touch base with that country. See Mangouras v. Squire Patton Boggs, 980 F.3d 88, 99–100 (2d Cir. 2020); In re Application of BM Brazil 1 Fundo de Investimento em Participações Multistratégia, 347 F.R.D. 1, 9–10 (S.D.N.Y. 2024). The analysis may have a second step. In In re B&C KB Holding GmbH, Germany had the predominant interest because the communications concerned German-law transactions, but the court ultimately applied U.S. privilege law because applying German law in the circumstances would have violated principles of comity: German law did not recognize attorney-client privilege in civil proceedings but also did not permit comparable pretrial discovery. No. 22-mc-00180 (LAK) (VF), 2025 WL 1802956, at *2–7 (S.D.N.Y. July 1, 2025). This approach is not a national default; other courts may apply different choice-of-law frameworks.

A foreign application’s relationship to a later U.S. patent does not necessarily establish a sufficient U.S. connection. In AstraZeneca LP v. Breath Ltd., No. 08-1512 (RMB/AMD), 2011 WL 1421800, at *5–9 (D.N.J. Mar. 31, 2011), communications concerning Swedish and PCT applications did not touch base with the United States merely because those applications supported priority to a later U.S. patent, the PCT application designated the United States, and a U.S. filing was contemplated. The communications concerned Swedish patentability and application preparation, so Swedish law governed. An email addressing several countries may therefore require subject-by-subject, and sometimes portion-by-portion, analysis.

C.                 Foreign lawyers and foreign patent practitioners

If U.S. law applies, the participant’s status remains important. A qualified foreign attorney-at-law acting as a lawyer ordinarily can participate in a privileged relationship, provided the communication is confidential and made to obtain or provide legal advice. In a recent patent case, emails with Swedish counsel seeking patent advice remained privileged, and limited circulation to managers with a need to know did not waive protection. Mölnlycke Health Care US, LLC v. Greenwood Mktg., LLC, No. 22 Civ. 3719 (CS) (JCM), 2024 WL 4602138, at *5–7 (S.D.N.Y. Oct. 29, 2024). Communications between U.S. and foreign lawyers representing the same client need not include the client on every message. Scheduling, billing, filing confirmation, and predominantly commercial discussions remain outside the privilege merely because lawyers sent them.

The analysis is less settled when the foreign associate is a nonlawyer patent practitioner. Queen’s University concerned registered U.S. patent agents; it did not itself decide the treatment of foreign practitioners. Several district courts nevertheless have extended its functional reasoning, subject to proof that the foreign practitioner was authorized to perform the particular services at issue.

In Knauf Insulation, LLC v. Johns Manville Corp., No. 1:15-cv-00111-TWP-MJD, slip op. at 5–11 (S.D. Ind. Oct. 1, 2019), the court protected communications with a regulated U.K. patent attorney to the extent they fell within the practitioner’s authority under U.K. law. Align Tech., Inc. v. 3Shape A/S, Nos. 17-1646-LPS & 17-1647-LPS, 2020 WL 1873026, at *2 (D. Del. Apr. 15, 2020), similarly concluded that communications with a registered foreign patent agent may be protected when the agent acts within the practice authorized by the agent’s home country.

Philips N. Am. LLC v. Fitbit LLC, 583 F. Supp. 3d 251, 259–70 (D. Mass. 2022), demonstrates why evidence of authority matters. The court accepted that the functional reasoning of Queen’s University, Knauf, and Align could extend to a foreign patent practitioner. Philips nevertheless failed to establish that the Dutch Patent Attorney’s disputed licensing and infringement communications were made within his legally authorized role. Evidence of a professional confidentiality duty was insufficient because professional secrecy is not necessarily an evidentiary privilege. Chervon adds the procedural warning: blanket assertions, an inadequate log, and failure to prove the foreign practitioner’s status and authorized function can forfeit the claim. No. 19-1293-GBW, slip op. at 3–8.

D.                 Communications between U.S. counsel and the foreign associate

U.S. counsel’s communication with a foreign associate may remain privileged because the associate serves as counsel to the same client or is a representative reasonably necessary to provide legal services. In Tulip Computs. Int’l B.V. v. Dell Comput. Corp., 210 F.R.D. 100, 104–05 (D. Del. 2002), communications between U.S. patent counsel and a Dutch patent firm concerning filing and prosecution of a U.S. patent were protected where the Dutch firm provided services to the client and acted as its agent in dealing with U.S. counsel. Similar reasoning may cover a foreign practitioner’s local-law analysis or a legally informed translation necessary to formulate prosecution advice.

Merely copying a foreign associate does not establish necessity, however. Nor should U.S. counsel rely reflexively on a “supervision” theory when U.S. counsel is not authorized to direct the practice of foreign law. Engagement records should identify the client, the practitioner’s credentials and authorized function, the legal task, the relationship to U.S. counsel, and the expectation of confidentiality. Labels and unsworn representations are not a substitute for document-specific evidence. See Enanta Pharms., Inc. v. Pfizer Inc., No. 22-10967-DJC, slip op. at 3–5 (D. Mass. May 7, 2024) (requiring a stronger evidentiary showing and treating filing-status facts as unprivileged); Chervon, No. 19-1293-GBW, slip op. at 3–8.

An office-action exchange illustrates the categories. A foreign associate’s email stating only a response deadline, official fee, or filing confirmation ordinarily conveys administrative facts. An email analyzing the examiner’s rejection, recommending whether to amend, or requesting U.S. counsel’s view on preserving claim scope is much more likely to qualify. Draft responses and attorney comments may reveal confidential legal advice even though the final response will be disclosed to the patent office and may ultimately enter a publicly available file. The submitted paper is not privileged as to the deliberately disclosed material, but filing does not necessarily eliminate protection for rejected alternatives or confidential consultations that do not appear in the submitted paper or later-public file.

E.                  The PTAB-specific rule

PTAB trial proceedings have an express rule. Under 37 C.F.R. § 42.57, a qualifying communication with a foreign-jurisdiction patent practitioner that is reasonably necessary and incident to the practitioner’s authority receives the same federal privilege treatment as a communication with a U.S. attorney. The rule applies regardless of whether the foreign jurisdiction recognizes an equivalent privilege and expressly accommodates communications among multiple practitioners and their assistants. Rule on Attorney-Client Privilege for Trials Before the Patent Trial and Appeal Board, 82 Fed. Reg. 51,570, 51,572–75 (Nov. 7, 2017).

Its reach should not be overstated. Section 42.57 governs privilege in PTAB trial proceedings. It does not itself bind federal district courts, state courts, foreign tribunals, or foreign patent offices. District-court litigation still requires the applicable choice-of-law and common-law analysis.

Foreign-associate communications also may qualify independently as work product, but only when they satisfy the governing test for documents prepared in anticipation of litigation or for trial. Philips provides the useful contrast: some Dutch-practitioner emails failed the privilege analysis, yet the court protected communications tied to a documented enforcement strategy against identified companies. 583 F. Supp. 3d at 271–74. The court rejected the broader proposition that a licensing business almost always anticipates litigation. The focus remained the reason the particular document was created.

VIII.       When prosecution work becomes litigation work product

Routine prosecution usually does not satisfy the anticipation-of-litigation requirement. The fact that patents are obtained for potential enforcement, that competitors exist, or that a valuable patent may someday be litigated is generally too abstract. Otherwise, nearly every prosecution file would become work product, effectively erasing Rule 26’s litigation threshold. See Resh, Inc. v. Conrad, No. 22-cv-01427-EJD (VKD), slip op. at 3–5 (N.D. Cal. Feb. 23, 2024); Geomatrix Sys., LLC v. Eljen Corp., No. 3:20-cv-1900, 2022 WL 603029, at *2–3 (D. Conn. Mar. 1, 2022).

The analysis may change when a concrete dispute emerges. Relevant developments can include an infringement accusation, a cease-and-desist letter, a threatened declaratory-judgment action, retention of litigation counsel concerning an identified adversary, an adversarial post-grant proceeding, or a continuation or reexamination strategy developed in response to specific litigation. Recent pre-suit-testing decisions illustrate the required contrast. In Samsung Elecs. Co. v. Technical Consumer Prods., Inc., No. 1:23-cv-186, slip op. at 3–6 (D. Del. June 27, 2025), a contemporaneous privilege log tied testing to anticipated patent litigation and counsel’s mental impressions. The decision does not create a categorical date or result for prosecution materials; it shows the importance of contemporaneous, document-specific evidence.

The applicable test varies by circuit. Some courts ask whether the document was created “because of” anticipated litigation; others emphasize its primary motivating purpose or ask whether it would have been prepared in substantially similar form in the ordinary course. See Geomatrix, 2022 WL 603029, at 2–3. Graham Packaging Co., L.P. v. Ring Container Techs., LLC, No. 3:23-cv-00110, 2024 WL 1221178, at 4–5 (W.D. Ky. Mar. 21, 2024), accepted that pre-suit infringement testing can qualify but found the showing inadequate where the patentee supplied no testing dates, declaration, or compliant privilege log. Under any formulation, conclusory declarations that litigation was always possible are vulnerable. A persuasive showing identifies the anticipated dispute, when and why it became concrete, who requested the document, how the document differed from ordinary prosecution work, and how it was intended to assist the dispute.

That showing should be document specific. A single prosecution matter may contain:

•             an ordinary amendment prepared to overcome prior art, which ordinarily is not work product absent a litigation nexus;

•              

•             a privileged email to the client recommending the amendment;

•              

•             a litigation-counsel memorandum evaluating how the amendment might affect an identified infringement case, which may be both privileged and work product; and

•              

•             a final response submitted to the USPTO, which is not privileged as to its deliberately disclosed content and may later enter a publicly available application file.

•              

Opinion work product receives strong protection, but the label should not be used to skip the threshold. Counsel’s mental impressions in routine prosecution are not automatically opinion work product. First show that the material was prepared in anticipation of litigation; then assess whether it contains fact or opinion work product and whether any disclosure waived the protection. Compare Resh, No. 22-cv-01427-EJD (VKD), slip op. at 3–5 (no litigation nexus shown), with Samsung Electronics, No. 1:23-cv-186, slip op. at 3–6 (contemporaneous evidence established litigation-directed testing).

IX.             Applying the doctrines document by document

A defensible review avoids file-level assumptions and asks separate questions for each item.

Invention disclosure to counsel. A confidential disclosure primarily seeking patentability and application advice is a strong privilege candidate under Spalding, 203 F.3d at 805–07. Privilege does not shield the underlying facts, which may be sought from nonprivileged sources subject to relevance, proportionality, and other discovery limits. See Resh, No. 22-cv-01427-EJD (VKD), slip op. at 3–5.

Client email asking how to answer an office action. This is ordinarily privileged if confidential and directed to legal advice. It ordinarily is not work product when the response is routine prosecution.

Supervisor-associate analysis. This often is privileged when it requests or refines advice for the client, conveys client instructions, or reveals protected communications. See LKQ, 2023 WL 3200236, at 6–7; Burge, 2025 WL 2172466, at 12–13. It is not automatically privileged merely because two lawyers exchanged it, and administrative or status-only attorney emails are not privileged merely because lawyers exchanged them. See Huber, No. 19-342-GBW-SRF, slip op. at 10–11. Whether they must be produced remains a separate discovery question. Such analysis ordinarily is not work product absent a litigation nexus.

Internal draft response. A draft may be privileged to the extent it reveals confidential legal advice, client input, rejected arguments, or strategic alternatives. See Burge, 2025 WL 2172466, at *12–13. Draft status alone is insufficient, and each attachment requires separate review. Routine drafting ordinarily is not work product.

Counsel’s private notes. Notes may be privileged if they memorialize a protected client communication, but are not privileged merely because counsel authored them. They may be work product if they satisfy the governing anticipation-of-litigation test; routine prosecution notes may fall into the protection gap.

Communication with a U.S. patent agent. Protection depends on confidentiality, legal purpose, and whether the subject is within the agent’s authorized USPTO practice. General infringement or licensing advice falls outside the direct patent-agent privilege.

Communication with a foreign associate. Identify the participant’s exact status, determine governing law, establish authorized practice, and analyze the communication’s purpose. See Philips, 583 F. Supp. 3d at 259–70; Chervon, No. 19-1293-GBW, slip op. at 3–8; In re B&C KB Holding GmbH, 2025 WL 1802956, at *2–7. PTAB Rule 42.57 answers only the privilege question in proceedings governed by Part 42.

Administrative transmittal. Deadlines, filing receipts, public status information, budgets, and purely ministerial instructions generally are not privileged, although embedding such facts in a substantive privileged discussion does not necessarily waive the entire communication.

Final filed paper. A filed response, amendment, or declaration has been disclosed to the USPTO and may later become public; it is not privileged as to the content deliberately submitted. Protection for undisclosed drafts or communications must be analyzed separately.

Litigation-directed prosecution strategy. A continuation, reexamination, interview, or amendment may generate work product when a concrete identified dispute gives the material the litigation nexus required under the governing test. See Geomatrix, 2022 WL 603029, at *2–3. The ordinary prosecution purpose and the litigation purpose should be separated and documented where possible; contemporaneous evidence was decisive in Samsung Electronics, No. 1:23-cv-186, slip op. at 3–6.

X.                Waiver, exceptions, and the mechanics of discovery

Even a qualifying communication can lose protection through disclosure beyond the privileged relationship. Distribution lists should therefore reflect the people genuinely needed to obtain or provide legal advice. Limited circulation to managers with a need to know did not waive privilege in Mölnlycke, 2024 WL 4602138, at 5–7. By contrast, after determining that U.S. privilege law ultimately governed, In re B&C KB Holding GmbH found waiver as to twenty-eight documents shared with bankers and financial advisers whose role was not necessary to translate or interpret information for legal advice. 2025 WL 1802956, at 5–7. Translators and technical specialists can remain within the privilege when reasonably necessary, but their role should be documented rather than assumed.

When U.S. and foreign counsel represent the same client, their coordination generally does not require a common-interest doctrine. When they represent different clients—for example, an applicant and a licensee or two co-owners—common interest may become important. The doctrine generally preserves an existing privilege; it does not create one. In re Regents of the Univ. of Cal., 101 F.3d 1386, 1389–91 (Fed. Cir. 1996). A shared commercial objective or nondisclosure agreement alone may not establish the required common legal interest.

A recent patent-litigation decision also cautions against converting a narrow disclosure into blanket waiver. One email sent to both sides did not waive all otherwise privileged communications regardless of subject, and in-camera review—not public production—was the appropriate procedure for testing whether an attorney-client relationship existed. Trs. of Columbia Univ. v. Gen Digital Inc., No. 2024-1244, slip op. at 13–18 (Fed. Cir. Mar. 11, 2026). The decision arose from litigation counsel’s communications with a witness-client rather than patent prosecution, but its waiver and disclosure principles remain instructive.

Work-product waiver follows a different analysis. Disclosure to a nonadversarial third party does not always waive work product; disclosure to an adversary, or conduct substantially increasing the likelihood of adversary access, can. The same act may waive privilege but not work product, or vice versa. Samsung Electronics held that identifying the source of an accused component in a complaint did not, without more, waive protection for the underlying testing, particularly where the patentee disclaimed reliance on that investigation to prove infringement at trial. No. 1:23-cv-186, slip op. at 4–6. By contrast, Graham Packaging required disclosure of factual testing information that the complaint had affirmatively used to establish infringement while preserving the distinction between those facts and counsel’s opinion work product. No. 3:23-cv-00110, slip op. at 12–16 (W.D. Ky. Mar. 21, 2024).

Selective reliance on prosecution advice creates an additional subject-matter-waiver risk. In NimbeLink Corp. v. Digi Int’l Inc., No. 22-cv-2345 (NEB/DJF), slip op. at 6–11 (D. Minn. Apr. 12, 2024), a patentee intentionally relied on selected prosecution-counsel communications to answer inequitable-conduct allegations. The resulting waiver reached related continuation communications concerning the same prior-art and disclosure issues, but proportionality limited production rather than opening the entire continuation file. A party therefore should evaluate related applications and define any intentional prosecution waiver carefully before using selected advice as a litigation defense.

Privilege logs should be granular enough to carry the proponent’s burden without revealing the advice. Enanta Pharms., Inc. v. Pfizer Inc., No. 22-10967-DJC, slip op. at 3–5 (D. Mass. May 7, 2024), rejected patent-prosecution labels and unsworn assertions that did not establish the source and purpose of the claimed advice. Chervon likewise shows the risk of invoking the wrong privilege and making blanket assertions. No. 19-1293-GBW, slip op. at 3–8. A useful entry identifies the date, participants, client or matter, practitioner status, application or proceeding, legal purpose, and protection asserted. A foreign-practitioner entry should identify the country and authorized function. A work-product entry should describe the anticipated dispute and litigation purpose rather than merely state “prepared in anticipation of litigation.”

XI.             Conclusion

The identity of the sender is a signpost, not the answer. A confidential email between a supervising attorney and junior associate can be privileged even when the client is not copied, but only when the email functions as part of providing legal advice or carries protected client information. A communication with a foreign associate may remain within the legal team, but the associate’s professional status, authorized scope, governing law, and role must be established. A registered patent agent receives protection for advice within authorized USPTO practice, not for every legal or commercial question involving a patent.

Work product asks a different question. Routine prosecution ordinarily is not litigation preparation, and attorney mental impressions do not eliminate the need for an actual litigation nexus. Once a concrete dispute emerges, some prosecution-related documents may become work product, but the showing must explain why each document was prepared and how it differs from ordinary prosecution work.

The practical objective is not to treat the prosecution file as categorically privileged or protected from production. It is to preserve confidential legal consultation, recognize the narrower protection available to authorized patent practitioners, and document the point at which prosecution work genuinely becomes dispute preparation. Purpose, participants, confidentiality, authority, and litigation nexus—applied document by document—provide the most reliable path through the file wrapper’s shadow.