Shifting burden of proof in method patent infringement suits

By Chen Jian, Wan Rui Law Firm

A method patent is an invention patent for a craft or technical manufacturing process, as well as chemical, mechanical or craft methods, that are created for making a product. Proving an infringement has difficulties, as the manufacturing process of using methods is generally carried out on the premise managed and controlled by the defendant, and it is difficult for the plaintiff to enter legally, let alone to complete evidence gathering.

Exercising the method patent right has always been a difficulty in patent rights protection. This is particularly true for defending patents on product manufacturing methods that are not new, as the reversion of burden of proof cannot be claimed.


Commissioned authentication before patent litigation
Chen Jian
Managing Partner
Wan Rui Law Firm

Article 3 of the Several Provisions on Evidence in Civil Litigation Involving Intellectual Property Rights provides that the court may, under certain conditions, apply a shift in the burden of proof. This article will try to assist method patent holders in effectively exercising their rights and formulating practical and feasible strategies for defending their rights.

Where a product manufactured with a patented method is not a new product, the burden of proof can be shifted only after the plaintiff has adduced evidence for the following:

(1) The product manufactured by the alleged infringer is the same as the product manufactured using the patented method. Generally speaking, a rights holder can easily acquire a product manufactured by a defendant by notarised purchase, etc.

The patent description will commonly detail the specific molecular structure, chemical composition or performance of the manufactured product, making it relatively easy to determine whether the two products are the same. Technical features that cannot be directly discerned can be tested or appraised by a testing or authentication institution.

In practice, a test or appraisal report is used as evidence to show whether the two are the same product.

(2) There is a high likelihood that the product is manufactured by the alleged infringer using the patented method. “High likelihood” does not require the plaintiff’s evidence to reach the “high probability” standard, but instead to meet the “preponderance of the evidence” standard. However, it is not easy.

The rights holder is required to adduce sufficient evidence to convince the judge to apply a shift in the burden of proof. The author’s practice experiences and precedents show that the following points could be considered in adducing evidence.

First, the high likelihood of using the patented method can be evidenced by showing a connection between the steps particular to the patented method and the manufactured product. For example, from residual substances detected in the product, the substance used in the manufacturing process can be reasonably inferred; or from the surface marks on the product, the craft used can be reasonably inferred.

Second, the source of the technology can be used as substantiation. For example, if the defendant previously had access to the relevant patent technology or the defendant’s technology originated from the plaintiff’s technology, it can be shown that the likelihood is high.

For example, in Laiyang Henderson Bioproducts Management and Shandong Graceland Biotechnology v Cathay Biotech et al (2021), the defendant leased the production facilities of an uninvolved third party and directly went into production without conducting an environmental assessment.

However, in another case, the technology of the uninvolved third party was found to infringe the patented method. Accordingly, the court held that a higher likelihood existed that the defendant manufactured the product by the patented method.

Third, an appraisal report issued by an authentication institution or an expert opinion can be evidence.

(3) The rights holder has made reasonable efforts to prove that the alleged infringer used the patented method. The judicial interpretations do not specify in detail the criteria for determining “reasonable efforts” but, from the perspective of the legislative intent, this should be judged by considering the specific circumstances and the known facts of the case, as well as the capacity of the concerned party to adduce evidence, and the difficulty of collecting evidence.

First, if the rights holder has not even tried the most commonly used notarisation or evidence preservation, it is clear that reasonable efforts have not been made.

For example, in Chen Hanqing v Beijing Wumart General Supermarket (2019), the Beijing Intellectual Property Court held that the plaintiff did not make reasonable efforts as he failed to carry out notarisation in the course of purchasing the infringing products.

In Li Meng v Qingzhou Taibeier Composite Material (2019), the Shandong High People’s Court also held that the plaintiff failed to take reasonable measures to fix the evidence before and during the litigation, and therefore did not make reasonable efforts.

Second, reasonable efforts also require the exhaustion of available means to adduce evidence. As long as there are still unused lawful channels of obtaining evidence, the means of proof have not been exhausted and a judge may consider that the plaintiff has not made reasonable efforts.

For example, in Laiyang Henderson Bioproducts Management and Shandong Graceland Biotechnology v Cathay Biotech et al (2021), the plaintiff not only submitted a notarial certificate and test report, but also evidence obtained from administrative authorities such as the Environmental Protection Bureau, Customs, etc.

Accordingly, the Supreme People’s Court held that the plaintiff had made reasonable efforts after considering the difficulties and the cost of obtaining the evidence, the quantity of evidence, the relevance and probative force of the evidence, etc.

Although these judicial interpretations reduce the plaintiff’s burden of proof to a certain extent, the party bearing the major burden of proof is still required to exhaust all means of adducing evidence following the three conditions stated in the judicial interpretations, so as to at least preliminarily show the high likelihood of the facts claimed exist, and thereby strive to persuade the court to apply the shifting of the burden of proof.

Chen Jian is a managing partner at Wan Rui Law Firm. Wan Rui Law Firm is a member of Sanyou IP Group

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