Service Of Process In Cross-Border Litigation: Comparing U.S. And UPC Practice (Part 1)

1. Introduction

Service of process is one of the most fundamental steps in civil litigation. Proper service not only ensures that parties receive notice of legal proceedings and have an opportunity to exercise their procedural rights, but also establishes the court's authority to hear the case. In cross-border civil and commercial disputes, valid service is equally critical to the recognition and enforcement of foreign judgments.

Because legal systems take different approaches to service of process, navigating cross-border litigation can be particularly challenging. While international treaties provide a common framework, important differences remain between jurisdictions. This article examines the legal significance of service of process, compares the approaches adopted by civil law and common law jurisdictions, and explains the key service rules under the U.S. Federal Rules of Civil Procedure and the Unified Patent Court (UPC), together with the practical considerations for cross-border litigation.

2. The Legal Significance of Service of Process and Divergent Legal Approaches

The fundamental purpose of service of process is to satisfy the requirements of procedural due process. In the United States, this principle is rooted in the Due Process Clause of the Fourteenth Amendment and was clearly articulated by the U.S. Supreme Court in the landmark decision Mullane v. Central Hanover Bank & Trust Co. (1950).¹ The Court held that the method of service must be reasonably calculated to notify interested parties of the proceedings and give them an opportunity to present their objections.

Although this principle originated in U.S. law, it has much broader significance. Service is not considered effective simply because procedural formalities have been completed. The key question is whether the chosen method was reasonably likely to notify the defendant and provide a fair opportunity to respond.

Improper service may deprive the court of jurisdiction over the defendant and ultimately jeopardize the enforceability of any resulting judgment. In cross-border disputes, courts asked to recognize or enforce foreign judgments routinely examine whether service complied with applicable due process standards. Defective service may therefore result in the refusal to recognize or enforce an otherwise valid judgment, significantly increasing both costs and delays for the parties.

The procedural treatment of service differs fundamentally between common law and civil law jurisdictions, creating important challenges in cross-border litigation.

Common law jurisdictions generally adopt an adversarial, party-driven model in which responsibility for service rests primarily with the claimant or its legal representatives, while the court performs a largely supervisory role. Accordingly, service by private process servers, lawyers, or postal channels is widely accepted, reflecting a preference for procedural efficiency and party autonomy.

Civil law jurisdictions, by contrast, generally regard service of process as an exercise of judicial authority and therefore entrust it to the courts or other designated public authorities. This framework is consistent with the historical development of civil law systems, which place greater emphasis on judicial supervision and the exercise of state sovereignty.

The distinction becomes particularly significant in cross-border litigation. For example, U.S. law has historically permitted service by postal channels in certain circumstances, whereas many civil law jurisdictions regard such methods as inconsistent with their judicial sovereignty and have therefore objected to them under the Hague Service Convention.

3. The Hague Service Convention: The Cornerstone of Cross-Border Service

The Convention on the Service Abroad of Judicial and Extrajudicial Documents in Civil or Commercial Matters (the Hague Service Convention)² was adopted to establish a uniform framework for cross-border service of process and to reduce conflicts between different legal systems.

However, important differences remain. One of the most significant concerns Article 10, which permits service by postal channels unless the receiving state objects. China, Switzerland and Germany, among others, have formally objected to this provision in order to preserve judicial sovereignty. As a result, U.S. litigants generally avoid serving documents by mail in those jurisdictions and instead rely on the Convention's Central Authority mechanism.

Broadly speaking, methods of cross-border service fall into two categories: direct service and indirect service.

Direct Service

Direct service does not require the involvement of authorities in the receiving state. Common examples include diplomatic or consular service, postal service, personal service, agreed methods of service, electronic service and, in limited circumstances, service by publication.

These methods are generally faster and more efficient. Electronic service has become increasingly common, particularly as courts adopt digital case management systems. However, its validity usually depends on the recipient's prior consent and confirmation of receipt. Likewise, service by publication is generally regarded as a measure of last resort because it may not effectively notify the defendant.

Indirect Service

Indirect service requires the involvement of public authorities in the receiving state. It is typically carried out through judicial assistance mechanisms such as the Hague Service Convention or the EU Service Regulation (Regulation (EU) 2020/1784).³ Documents are transmitted through designated Central Authorities or diplomatic channels. Although this approach better respects national sovereignty, it is usually slower than direct service.

Choosing the appropriate method of service requires balancing efficiency, cost and legal compliance. The following sections examine how these principles operate in practice under the U.S. Federal Rules of Civil Procedure and the Unified Patent Court (UPC).

4. Service of Process under the U.S. Federal Rules of Civil Procedure

Service of process in U.S. federal litigation is governed primarily by Rule 4 of the Federal Rules of Civil Procedure (FRCP).⁴ The Rule is designed to balance procedural efficiency with due process by ensuring that defendants receive timely notice of the proceedings while allowing litigation to proceed without unnecessary delay.

Service on Domestic Corporate Defendants

Rule 4(h)(1) provides two principal methods for serving a corporation in the United States.

• FRCP 4(h)(1)(A): Service may be carried out in accordance with the procedural law of either the state where the federal court is located or the state where service is made. This gives plaintiffs flexibility to choose the most appropriate procedure for the circumstances of the case.⁵
• FRCP 4(h)(1)(B): The summons and complaint may be delivered directly to an officer, managing or general agent, or any other person authorized by appointment or law to accept service on the company's behalf.⁶

In practice, the second method is often preferred because it avoids the complexity of differing state procedural rules and usually enables service to be completed more quickly.

Service on Foreign Corporate Defendants: FRCP 4(h)(2) & FRCP 4(f)

Service on foreign corporations is governed by Rule 4(h)(2), which refers to the service provisions applicable to individuals under Rule 4(f), subject to certain exceptions. Rule 4(f) establishes three principal methods of service.

• Method 1 (FRCP 4(f)(1)): Where an applicable international agreement exists, service should generally be effected through that agreement, most commonly the Hague Service Convention.⁷
• Method 2 (FRCP 4(f)(2)): Where no applicable treaty governs service, or where the treaty does not specify the relevant procedure, Rule 4(f)(2) permits several alternatives, including service in accordance with the law of the destination country,⁸ service through letters rogatory,⁹ or, where permitted, service by mail requiring a signed receipt.¹⁰ Because letters rogatory are transmitted through diplomatic channels, they often take several months to complete and are generally used only where no treaty mechanism is available.
• Method 3 (FRCP 4(f)(3)): Rule 4(f)(3) also allows a court to authorize alternative methods of service, provided they are not prohibited by international agreements.¹¹ Email service is one of the best-known examples. Courts typically approve alternative service only where conventional methods have proved impracticable or ineffective.

Taken together, Rule 4(f) seeks to balance respect for international agreements with the practical need to ensure that litigation proceeds without undue delay.

Service Deadlines, Answer Periods & Waiver of Service

As a general rule, service must be completed within 90 days after the complaint is filed. If service cannot be completed within that period, the court may require the plaintiff to explain the delay and, where appropriate, dismiss the action without prejudice.

The 90-day deadline does not generally apply to service under Rules 4(f) or 4(h)(2). This exception is particularly important in cases involving Chinese defendants, as service through China's Central Authority under the Hague Service Convention often takes several months. Parties should therefore factor these delays into their overall litigation strategy.

Upon valid service of the summons and complaint, a domestic U.S. defendant generally has 21 days to file an answer or a Rule 12 motion. Rule 4(d) also establishes a waiver-of-service mechanism designed to reduce the costs of formal service. A defendant who timely returns a waiver is not required to be formally served and instead has 60 days to respond to the complaint if located within the United States, or 90 days if located outside the United States, calculated from the date on which the waiver request was sent. This mechanism provides both parties with additional time to prepare their cases while avoiding the costs associated with formal service.

Taken together, the U.S. approach reflects the adversarial nature of its litigation system by placing primary responsibility for service on the parties. At the same time, strict compliance with the service rules remains essential, as defective service may ultimately undermine the enforceability of any judgment.

5. Service of Process and Response Deadlines before the Unified Patent Court (UPC)

Unlike the U.S. federal system, where responsibility for service largely rests with the parties, the Unified Patent Court (UPC) adopts a court-led approach. Under Rule 271 of the UPC Rules of Procedure, once a Statement of Claim has been filed, responsibility for serving the defendant rests with the UPC Registry rather than the claimant. This reflects the civil law tradition, under which service of process is generally regarded as a judicial function.

The UPC also operates through its electronic Case Management System (CMS). Once a party is represented by a registered legal representative, subsequent service is generally completed electronically through the CMS, removing the need for paper-based service and making case administration more efficient.

Service within UPC Member States

The UPC adopts a tiered service hierarchy for parties domiciled within Member States:

a. Primary tier: Electronic service (subject to Regulation (EU) 2020/1784 Article 19)¹²

Electronic service is the preferred method wherever possible. Documents may be sent to:

• An electronic address designated by the defendant for receiving court documents;
• The registered electronic inbox of the defendant's legal representative¹³; or
• A representative authorized to accept service on the defendant's behalf.

Electronic service is valid only if two conditions are satisfied:

• The recipient has expressly agreed to receive documents electronically; and
• The recipient confirms receipt, including the date of delivery.

b. Secondary tier: Registered postal service

Where electronic service is unavailable or unsuccessful, the Registry may serve documents by registered post with proof of delivery.

c. Tertiary tier: Alternative court-authorized service

If neither electronic nor postal service is practicable, the court may authorize an alternative method of service in accordance with the law of the relevant Member State, provided there is good reason to do so.

This graduated approach seeks to balance procedural efficiency with consistency across participating Member States.

Service on Defendants Outside the UPC (Including China)

Where the defendant is located outside the UPC's participating States, Rules 273 and 274 establish a separate framework for cross-border service.

• Primary cross-border channels: Where applicable, the Registry serves under the EU Service Regulation. Otherwise, the Hague Service Convention or another applicable international treaty will normally govern the process. In the absence of any treaty, diplomatic or consular channels may be used.
• Fallback alternative service:If these methods prove unsuccessful, the UPC may authorize alternative service where permitted by the law of the destination state and justified by the circumstances of the case.

The UPC seeks to promote efficient cross-border litigation while respecting the sovereignty of non-Member States.

UPC Procedural Timelines for Response

Once service has been completed, defendants must respond within a series of procedural deadlines.

• Preliminary Objections:Defendants wishing to challenge the UPC's jurisdiction or other procedural issues must file preliminary objections within one month of service. Importantly, filing such objections does not automatically suspend the deadline for filing a substantive defense.
• Substantive Statement of Defence: The Statement of Defence must be filed within three months after service. It should include the defendant's factual and legal arguments, claim construction, supporting evidence and witness evidence where appropriate.
• Revocation Counterclaim:Where the defendant challenges the validity of the asserted patent, any counterclaim for revocation must be filed together with the Statement of Defence and supported by the relevant facts, legal grounds and evidence.
• Key Takeaways for Chinese Companies Facing Cross-Border Litigation

For Chinese companies named as defendants in U.S. federal litigation or UPC proceedings, one of the most important procedural safeguards is the Hague Service Convention. In most cases, claimants seeking to serve a Chinese defendant must use the Convention's Central Authority mechanism through China's Ministry of Justice. Although this process often takes several months, compliance with the Convention is generally essential to ensure that service is legally valid.

In practice, some U.S. plaintiffs seek to expedite the proceedings or increase litigation pressure on Chinese defendants by serving documents on a Chinese company's U.S. subsidiary or branch, arguing that the subsidiary qualifies as a "managing or general agent" under Rule 4(h)(1)(B). In doing so, they seek to effect domestic service within the United States rather than proceeding through the Hague Service Convention's Central Authority mechanism. Whether such service is effective depends on the specific facts of each case. Chinese companies should therefore assess carefully whether the applicable service requirements have in fact been satisfied before responding to the proceedings.

Where a claimant has neither attempted service under the Hague Service Convention nor obtained a court order authorizing alternative service under Rule 4(f)(3), defendants may, where appropriate, challenge the adequacy of service under Rule 12(b)(5). This provides an important procedural safeguard against litigation proceeding on the basis of ineffective service.

Service of process is often regarded as a procedural formality. In cross-border litigation, however, it can have significant strategic consequences. The effectiveness of service may determine not only when proceedings begin, but also whether a court has jurisdiction, whether a judgment can later be enforced, and how much leverage each party holds throughout the litigation.

For in-house counsel and IP practitioners, service of process should therefore be regarded as an important strategic consideration rather than a purely administrative step. A sound understanding of the applicable service rules can help companies protect their procedural rights and respond more effectively to cross-border disputes.

This article is the first in a two-part series. Part 2 will examine additional cross-border service issues and the practical challenges that arise in different jurisdictions, with a particular focus on the strategic considerations for companies involved in international patent disputes.

Footnotes

1. Mullane v. Cent. Hanover Bank & Tr. Co., 339 U.S. 306, 314 (1950) (holding that notice reasonably calculated, under all the circumstances, to apprise interested parties of the pendency of the action is a fundamental requirement of due process).

2. Convention on the Service Abroad of Judicial and Extrajudicial Documents in Civil or Commercial Matters art. 10, Nov. 15, 1965, 20 U.S.T. 361, 658 U.N.T.S. 163 [hereinafter Hague Service Convention] (stating that the Convention shall not interfere with the freedom to send judicial documents by postal channels directly to persons abroad, provided the State of destination does not object).

3. Regulation (EU) 2020/1784 of the European Parliament and of the Council of 25 November 2020 on the Service in the Member States of Judicial and Extrajudicial Documents in Civil or Commercial Matters, 2020 O.J. (L 405) 40.

4. R. Civ. P. 4.

5. R. Civ. P. 4(h)(1)(A) (incorporating Fed. R. Civ. P. 4(e)(1), which permits service by "following state law for serving a summons in an action brought in courts of general jurisdiction in the state where the district court is located or where service is made").

6. R. Civ. P. 4(h)(1)(B) ("by delivering a copy of the summons and of the complaint to an officer, a managing or general agent, or any other agent authorized by appointment or by law to receive service of process and—if the agent is one authorized by statute and the statute so requires—by also mailing a copy of each to the defendant").

7. R. Civ. P. 4(f)(1) ("by any internationally agreed means of service that is reasonably calculated to give notice, such as those authorized by the Hague Convention on the Service Abroad of Judicial and Extrajudicial Documents").

8. R. Civ. P. 4(f)(2)(A) ("as prescribed by the foreign country's law for service in that country in an action in its courts of general jurisdiction").

9. R. Civ. P. 4(f)(2)(B) ("as the foreign authority directs in response to a letter rogatory or letter of request").

10. R. Civ. P. 4(f)(2)(C)(ii) ("using any form of mail that the clerk addresses and sends to the individual and that requires a signed receipt").

11. R. Civ. P. 4(f)(3) ("by other means not prohibited by international agreement, as the court orders").

12. Regulation (EU) 2020/1784 art. 19, 2020 O.J. (L 405) 40 (setting out the requirements for electronic service):

• Prior consent: The recipient must explicitly consent to receive filings via the specified electronic address, notified to the court or claimant.

• Post-delivery confirmation: The recipient must submit a formal acknowledgement of receipt recording the exact delivery date.

13 Agreement on a Unified Patent Court art. 48, Feb. 19, 2013, 2013 O.J. (C 175) 1 (defining legal representatives to include qualified lawyers authorized to practice in UPC contracting states and European Patent Office patent attorneys).