In China’s judicial system, the fundamental principle of adjudication based on facts and law places evidence at the highest level of importance, often referred to as the “king of legal proceedings.” Unlike the United States, where pretrial discovery is common, China’s legal system requires plaintiffs to bear the burden of proof under the rule that “whoever makes a claim must prove it.” This creates significant challenges in gathering evidence, especially in intellectual property infringement cases. Patent owners must prove three key points: that infringement actually occurred, that the defendant is legally responsible, and the amount of damages owed. These difficulties are even greater in cases involving process patents, large industrial equipment, and B2B products, where infringing acts often take place inside secure facilities inaccessible to rights holders. As a result, the inability to obtain crucial evidence often leads to insufficient compensation, weakening the effectiveness of patent enforcement. Drawing on extensive litigation experience and landmark cases, this analysis offers strategic approaches for collecting evidence and overcoming these challenges within China’s judicial system.
Legal Basis for Proving Patent Infringement
Article 11 of China’s Patent Law clearly forbids unauthorized use of patented inventions, utility models, or designs. This includes manufacturing, using, offering for sale, selling, or importing patented products, as well as directly applying patented processes or exploiting products obtained through patented processes without permission. The main challenge for patent holders is to definitively prove that the alleged infringer has engaged in one or more of these prohibited activities. Therefore, effectively gathering legally admissible evidence is essential for winning cases in this jurisdiction.
Key Evidence Collection Techniques
Notarized Purchase of Suspected Infringing Products
The importance of a notarized purchase cannot be overstated. Conducted under the official supervision and certification of a state-authorized notary public, this method involves buying the suspected infringing product to establish a verifiable chain of custody. Because courts in China rigorously scrutinize evidence for authenticity and tampering, non-notarized purchases are vulnerable to challenges regarding their legitimacy and origin, which can lead to their rejection or reduced evidentiary value. Thus, a carefully executed notarized purchase is one of the most reliable and persuasive ways to prove infringement, especially for direct sales or offers to sell.
However, notarizing purchases of specialized B2B products is far more complex than consumer goods transactions. Sales channels for industrial machinery, custom chemical products, or proprietary components are often deliberately opaque and restricted. Rights holders must conduct thorough intelligence gathering before notarization. Hiring specialized investigators to research the target company’s operations, production capacity, distribution networks, sales procedures, and key personnel is essential. This groundwork helps identify feasible purchasing methods and establish contacts within the target organization.
Case Example: In a major invention patent infringement case handled by our firm, the disputed product was a highly specialized industrial item with no open market availability. Initial investigations indicated that obtaining samples was nearly impossible. Through persistent fieldwork and discreet inquiries within the relevant industry network, we discovered that the alleged infringer relied on an authorized regional dealer network. By approaching this dealer under a carefully planned pretext, we successfully purchased multiple product samples under full notarial supervision. This case highlights the critical importance of thorough due diligence and creative investigative strategies in overcoming seemingly insurmountable evidence obstacles.
The evidentiary strength of a notarized purchase is multifaceted. Importantly, if the bought product or its packaging displays the manufacturer’s name, registered logo, corporate address, unique model numbers, or traceable batch codes, it offers direct, concrete proof linking that specific entity to the physical creation and commercial sale of the infringing item. This connection is crucial for overcoming denial defenses and holding manufacturers accountable. Additionally, the physical product itself serves as an essential reference for detailed technical comparisons against the patented claims, providing the scientific and factual basis for determining infringement.
Manufacturers often try to avoid liability by asserting that purchased products are unauthorized counterfeits. Without strong, independent evidence supporting such claims—like verified counterfeiting reports from industry groups or forensic analyses revealing significant quality differences from genuine items—courts generally accept that products bearing authentic manufacturer identifiers originate from that manufacturer. A notarized purchase greatly strengthens the evidence against these defenses.
The most difficult cases involve acquiring unmarked products lacking any identifying details. When such infringing items are bought from a seller, the patent holder faces the challenge of proving that the seller manufactured the product rather than merely distributing it. Investigations must focus closely on the seller’s registered business scope, corporate registration documents, public promotional materials, and verifiable production capabilities. Strong evidence may include: official business registration records explicitly listing manufacturing as part of the approved activities; company websites, catalogs, or brochures claiming in-house design and production; and detailed technical specifications or proprietary product documents authored by the seller. If this evidence establishes the seller’s manufacturing capacity and the seller cannot credibly name another source when formally questioned or legally compelled, courts may reasonably conclude that the seller is the manufacturer. Our litigation experience includes successful cases where unmarked products purchased from sellers were attributed to those sellers as manufacturers based on this comprehensive business evidence, resulting in injunctions against production and significant damages awards.
On the other hand, if the seller clearly operates only as a distributor—such as a registered trading company without physical facilities, equipment, or manufacturing claims—the litigation approach must adapt. The focus should shift to using legal tools to compel disclosure of the product’s source. Article 64 of the Patent Law and related judicial interpretations provide means to require distributors to reveal their upstream suppliers, enabling identification of the actual manufacturer for further legal action and reducing overall liability exposure.
For large industrial equipment where physically obtaining the items is too costly or impractical, a complex, multi-step strategy for preserving evidence is crucial. In a notable case involving patented large-scale chemical production machinery, our method included: gathering initial evidence from the unauthorized manufacturer’s publicly available website specifications and technical promotional materials showcased at major international trade shows, along with detailed technical data taken from public tender documents issued by the end-user; filing a preliminary infringement lawsuit based on this initial evidence; quickly requesting a formal evidence preservation order from the court under Article 84 of the Civil Procedure Law; and organizing a court-supervised on-site inspection with appointed technical experts to carefully record the specific features of the allegedly infringing equipment for thorough comparison with the patent claims. This organized, step-by-step approach effectively overcame the challenge of lacking physical evidence at the start.
For B2B transactions, it is vital to maintain continuous timing throughout the notarization process. Complex deals involving contracts, purchase orders, payments, and deliveries often take days or weeks. Each individual step must be notarized promptly and consecutively to preserve an unbroken, verifiable chain of custody. Importantly, qualified intellectual property litigation attorneys should be involved before any notarization begins. Legal counsel must direct the investigation plan, design compliant purchase scenarios, and carefully review the draft notarial deed to ensure it accurately reflects the entire process, correctly names all participants and locations, and clearly describes the evidence obtained. We have seen many cases where third-party investigators produced notarial deeds with serious errors—such as inconsistent participant lists, gaps in timing, incomplete descriptions, or unclear links to the evidence—which greatly weakened their admissibility or failed to effectively implicate the intended party. Therefore, proactive and expert legal supervision throughout the evidence collection process is essential to maintain evidentiary integrity and maximize impact in court.