Service of Process by Email Halted: How the Smart Study Case Reshapes Cross-Border E-Commerce IP Litigation

On December 18, 2025, the U.S. Court of Appeals for the Second Circuit issued its decision in Smart Study Co., Ltd. v. Shenzhenshixindajixieyouxiangongsi, No. 24-313 (2d Cir. Dec. 18, 2025). The case directly addressed a recurring issue in cross-border e-commerce and intellectual property litigation: when a defendant is located in China or another foreign country, may a plaintiff seek court authorization under Federal Rule of Civil Procedure 4(f)(3) to serve the complaint by email, without complying with the procedures of the Hague Service Convention?

The significance of this decision does not lie in the fact that it discussed electronic service of complaints, summonses, and temporary restraining orders (TROs) for the first time. Rather, its importance stems from its highly structured interpretation of the nature of the Hague Service Convention, and its rejection of the argument that “if the Convention does not expressly prohibit email service, then email service is permissible.”

I. Background and Formation of the Dispute

The Smart Study case involved an intellectual property dispute in which the plaintiff attempted to serve process on a defendant located in China. China is a signatory to the Hague Service Convention and has formally objected to service by postal channels under Article 10 of the Convention. Instead of serving through China’s designated Central Authority, the plaintiff sought court approval to serve the Chinese defendant by email.

The district court granted the request. However, once the case reached the Second Circuit, the central question became: when the defendant’s address is known, and China is a Convention member that has lodged relevant objections, may service still be effected by email under Rule 4(f)(3)?

On December 18, 2025, the Second Circuit reversed the lower court’s authorization of email service.

II. The Core Logic of the Decision: The Convention as a “Closed System,” Not “Silence Means Permission”

The Smart Study ruling did not center on whether email qualifies as a “postal channel.” Instead, the court focused on the structural design of the treaty itself. It emphasized that the Hague Service Convention is not an “open-ended” framework, but an institutional arrangement that affirmatively enumerates and establishes permissible methods of service. In other words, when the Convention applies, lawful cross-border service must fall within the mechanisms created by the Convention.

The court relied on Volkswagenwerk AG v. Schlunk, 486 U.S. 694 (1988), where the Supreme Court held that the Convention is mandatory when judicial documents must be transmitted abroad for service. It also cited Water Splash, Inc. v. Menon, 581 U.S. 271 (2017), which interpreted the Convention’s structure and underscored that, within its scope, the Convention preempts inconsistent methods of service.

Based on this framework, the Second Circuit articulated a key principle: if a method of service is not authorized within the Convention’s framework, then when the Convention applies, that method is not merely “not prohibited,” but rather “not permitted.” This formulation effectively treats the Convention as a closed and exclusive system.

Thus, even though the Convention does not mention “email,” one cannot conclude that email service is therefore allowed. Especially in light of China’s objection to Article 10 service methods, the court held that Rule 4(f)(3) should not be used to construct a pathway around the Convention.

III. The Status of Rule 4(f)(3): It Cannot Override a Treaty

Smart Study also addressed a view long held by some district courts: that Rule 4(f)(3) stands on equal footing with Rule 4(f)(1), and that plaintiffs need not first attempt Hague service before seeking court authorization for alternative service.

The Second Circuit did not deny the independent existence of Rule 4(f)(3). However, it emphasized that the rule applies only to methods “not prohibited by international agreement.” When an international treaty establishes a governing framework, domestic procedural rules cannot provide an escape route from that framework. Under U.S. law, treaties hold superior authority and cannot be undermined through rule interpretation.

This constitutes the decision’s most important institutional implication: it explicitly implements the treaty-preemption principle in the context of cross-border electronic service.

IV. “Address Unreliable” vs. “Address Unknown”: Two Distinct Legal Propositions

The logic of Smart Study makes the issue of “unknown address” a critical practical battleground. Under Article 1 of the Hague Service Convention, the Convention does not apply when the address of the person to be served is unknown. This creates potential space for Rule 4(f)(3).

However, in cross-border e-commerce infringement cases, plaintiffs often argue that the physical addresses registered on online platforms may be false or unverified, and therefore “unreliable.” Here, a crucial distinction must be made.

“Address unknown” refers to an objective inability to ascertain the defendant’s address. After reasonable investigation and diligent efforts, no serviceable location can be identified. This is a factual state of nonexistence.

By contrast, “address unreliable” means that an address exists, but its authenticity is questioned, or the plaintiff fears that service may fail. This concerns doubts about accuracy, not factual absence.

This distinction is logically decisive. If mere suspicion about an address’s reliability were sufficient to render it “unknown,” then virtually any cross-border e-commerce case could bypass the Hague Convention through a simple declaration. The Convention’s scope would be systematically weakened. The treaty’s design seeks to ensure procedural certainty and predictability in service of judicial documents among member states.

Accordingly, from a treaty-interpretation perspective, “unreliable” cannot automatically be equated with “unknown.” The latter requires stronger objective proof, such as unsuccessful reasonable investigations and the inability to confirm any physical address through available channels. Mere subjective doubt is insufficient to exclude the Convention’s application.

V. Circuit-Level Approaches to Service of Process by Email in Cross-Border E-Commerce Cases

Within the Second Circuit (which includes New York), Smart Study now constitutes binding appellate precedent. When the Convention applies and China is the destination country, service of process by email will be difficult to obtain unless the plaintiff can first demonstrate that the defendant’s address is truly unknown.

In the Fifth Circuit (which includes Texas), there is currently no appellate decision directly addressing email service to China in the same explicit manner as Smart Study. Existing precedents recognize the independence of Rule 4(f)(3), but also stress the importance of respecting treaty frameworks when applicable. The circuit’s future direction remains to be seen.

In the Seventh Circuit (including Illinois) and the Ninth Circuit (including California), no unified appellate rule comparable to Smart Study has yet been established. Some district courts in e-commerce infringement cases have approved email service, often based on a more flexible interpretation of Rule 4(f)(3). The emergence of Smart Study subjects those practices to stronger treaty-preemption challenges.

Overall, the United States has not yet developed a uniform nationwide rule regarding email service on defendants in China. However, the Second Circuit has clearly adopted a strict treaty-interpretation approach. Whether other circuits will follow remains an important development to watch in cross-border litigation in the coming years.

VI. Conclusion

The significance of Smart Study does not lie in a simple rejection of email service. Rather, it redefines the hierarchical relationship between treaties and procedural rules. It shifts the focus from whether a technological method is efficient to whether the treaty framework is exclusive. At the same time, it makes “address unknown” a critical legal threshold, while making clear that “address unreliable” is insufficient to automatically trigger an exception to the Convention.

As cross-border e-commerce cases continue to grow, this ruling will shape service strategies, the stability of default judgments, and future disputes over void judgments under Rule 60(b)(4).

Note: Each federal circuit court of appeals serves as the superior court for the district courts within its jurisdiction, and its precedents are binding only within that circuit.

(Disclaimer: The information published herein is for reference only and should not be regarded as legal authority or advice on any subject. All rights reserved. Reproduction requires permission from Allbelief Law Firm.)