Case Study: Prior Use Defense in Patent Infringement Litigation

  Published on November 2, 2022

Prior use can be an effective defense in patent infringement litigation. In the second instance of Shanghai Dingxiang Environment Technology Co., Ltd. (“Plaintiff”) vs. Shanghai Fuyu Environment Environment Technology Co., Ltd. (“Defendant”), IP tribunal of Supreme People’s Court decides that prior use is established and therefore the defendant’s activity does not constitute infringement.

According to Patent Law of P.R. China,
Article 75 None of the following shall be deemed an infringement of the patent right:

(2) Where, before the date of filing of the application for patent, any person, who has already made the identical product, used the identical process or made necessary preparations for its making or using, continues to make or use it within the original scope only;

The case is related to a patent entitled “A Water Treatment Box Device” with application date of March 11, 2016. The Plaintiff filed a lawsuit against the Defendant for patent infringement. In the litigation, one of the defendant’s defense is that before the filing date of the patent, it has started to produce the identical product (prior use).

Here below is the evidence of prior use submitted by the Defendant:

(i) Email regarding the details of the product

An email dated March 4, 2016, sent by Zhiyi CHEN, who is the employee of the Defendant, to its sales agent, providing photo of the product. The Court believes that the board structure, U-shaped rail and movable part, which are the three distinguishing features, are disclosed in the photo. In order to be admitted by the court, the email has been notarized by the Notary Public.

In accordance with Chinese patent practice, distinguishing features are the technical means/technical solutions which are different from the prior art and adopted by the inventor through creative work to solve technical problems/achieve invention tasks.

The Court believes that the technical problem to be resolved by the Plaintiff’s patent is as follows:

Since the opening and closing of the box door is a rotary motion, rather than a linear insertion, in order to realize the insertion of the board, the size of the board has to be reduced, or the interval between the boards has to be enlarged. In this case, on the one hand, it will cause a waste of space, on the other hand, due to the reduction of the distance between the boards, as well as the reduction of the board size, the processing capacity will be weakened. As provided in the 14th paragraph of the description, the technical solution is introduction of board structure, rail and movable part. Therefore, these three features should be deemed as distinguishing features and they are clearly illustrated in the photo attached in the email.

The first instance Court believes the photo in the attachment fails to disclose all the technical feature of the patent claim. IP Tribunal of Supreme Court disagrees on the matter. Zhiyi CHEN, who is the employee of the plaintiff, used to be one of the shareholders of the plaintiff. In the Share Withdrawal Agreement between Zhiyi CHEN and the Plaintiff, it is provided that Zhiyi CHEN is allowed to be engaged in business competitive with the Plaintiff’s current lines of business after he leaves the Plaintiff. In addition, the Plaintiff also confirms the fact that the Defendant manufactures and sells an old model of water treatment device. Therefore, the Court holds that all the other features undisclosed in the photo should be deemed as necessary technical features of prior art.

(ii) Other evidence

1) A hand stretched drawing by the supplier of the Defendant dated November 16, 2015
2) The delivery date of the Defendant’s product to its client is March, 2016.

The Court believes that in spite of the fact that each evidence above alone is not sufficient in proving the patented solution has been used before the application date, by comprehensive consideration of all relevant evidence, it can be proved that the Defendant has started to manufacture the product identical to patented product. Therefore, the Defendant’s activity does not constitute infringement.

Takeaway of this case

(i) Evidence of product sales with product details (such as photo, brochure, drawings etc.) should be preserved well, preferably in the form in which date of sales / manufacture can be proved later (such as email, posts in social media platform, blog etc.)
(ii) Even if single evidence is not sufficient in disclosing all features, if there are other supporting evidence, it is still possible to prove prior use.