Drafting the best background section of patent applications

Author:Yali Shao, Ziqing Wu | UpdateTime:2020-04-14 | Hits:

How much disclosure is appropriate for the background section of a patent application? This question is difficult to answer, especially when it applies to a multinational application as different countries have different regulations regarding the background section of the application. For example, in some countries, the background section may constitute the applicant's admitted prior art (AAPA) against the invention claimed to be protected. Accordingly, it is important to know the regulations of different countries and draft a ‘one size fits all’ background section for a multinational application.

Practice in China

Generally speaking, in China, the background section does not constitute prior art against the invention claimed to be protected unless it is proved by a prior art document or other prior art evidence (ie, the AAPA principle is generally not applicable in China).

According to the Patent Examination Guidelines of the Patent Law, ‘prior art’ includes any technology which has been disclosed in publications in China or abroad, or has been publicly used or made known to the public by any other means in China or abroad, before the date of filing or the priority date where priority is claimed. Publications in the context of the Patent Law shall indicate or have other evidence to prove the date of public issue or publication. In other words, the date of public use or publication should be proved before the publication is regarded as prior art. Therefore, if there is no evidence to prove that the background section was known to the public, the examiner at the patent office or Patent Re-examination Board, or the judge at the court will not regard the background section as prior art.

Legal practice under the Patent Law verifies the above conclusion. For example, in Bing v the Patent Re-examination Board the patentee, Hu Bing ‒ who owned Chinese Patent ZL 01213645.X ‒ admitted in the oral hearing of the invalidation procedure that the content recorded in the background section belonged to prior art of the patent. As a result, the Patent Re-examination Board made the invalidation decision that Claim 1 did not have inventiveness in view of the combination of the prior art admitted by Bing and Reference 2. Bing was not satisfied with the board’s decision and initiated an administrative lawsuit before the Beijing Intermediate Court, taking the board as the defendant. However, the first trial maintained the board’s decision, so Bing appealed to the Beijing High People’s Court. The court overturned the first judgment and made the final judgment that the patentee’s self-admission of prior art in the oral hearing did not mean that the background section of the patent belonged to the prior art.  

According to the court:

“in this case, even though Hu Bing admitted that the technology described in the first page of the present patent specification belongs to prior art, the prior art is actually defined as technology which has been disclosed in publications in China or abroad, or has been publicly used or made known to the public by any other means in China or abroad, before the date of filing. Once the prior art self-admitted by Hu Bing is confirmed by the law, anyone may file an invalidation against others’ patents based on this confirmation, that is, Hu Bing’s self-admission may harm the interests of others, so Hu Bing's self-admission behavior should be restricted, which does not have legal binding.”

Further, a patent invalidation decision by the Patent Re-examination Board in 2012 with regard to Chinese Patent ZL 201020666050.0 evidenced a change in the board’s attitude towards the AAPA. In this invalidation decision, the board did not regard the patentee’s AAPA as prior art. According to the board:

“though the background technology appears in the form of prior art, it only shows it is known to the Merry Company itself, but cannot indicate that it is made known to the public in the general sense before the time of filing, so in the absence of other evidence to prove its publicly issue or publication date, the content in the Background [section] is taken as being known to the public at the publication date of the very patent along with its specification, which cannot be regarded as being in public status before the filing date of the patent according to the Patent Law, and thus cannot be used as the prior art relative to the Background [section] in the patent to assess the novelty and inventiveness.”

The subsequent first judgment of the Beijing Intermediate Court in Zhao v the Patent Reexamination Board supported the above decision, as did the Guangdong High Court’s final judgment in Yingjiaxun Industry v He Xin Precision Electronics (Dongguan) Co, Ltd with respect to Chinese Patent ZL 200620057997.5.


The above case law demonstrates that the background section is safe under existing practice in China, since the AAPA principle is generally not applicable. However, considering the fact that, in certain circumstances, the AAPA may be applicable in other jurisdictions such as the United States, Europe, Korea and Japan, it is possible that a third party could analyse the application and examination history of a patent in China and use this to support their opinions against its family patent in other countries. Therefore, applicants should be cautious when drafting the background section of an application to be filed in China, especially if the application is also intended to be filed in other countries. In such cases, applicants should also avoid admitting explicitly in the description, spoken or written opinion at a later stage (eg, in the response to the office action) or in the invalidation procedure that the background section belongs to the prior art in order to avoid unnecessary trouble. The basic strategy is to make the background section as short as possible. If a detailed background description is inevitable for the purpose of clearly describing the invention, it is better to add this content to the detailed description, rather than the background section.

This article has been published on iam.