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  • He Zhao

Why is it Sometimes Difficult to Enforce My Patent in China? - Functional Technical Features in Product Claims

Many applicants have secured numerous patents in China, but when it comes to enforcement, they often find it challenging to protect their inventions. A common issue arises with product claims containing functional features.


In infringement cases, the protection scope defined by functional features is narrowed to the embodiments specified in the specification, rather than all potential embodiments covered by those features. This means that even if a suspected infringing product falls within the functional feature scope, the court may not rule in favor of infringement unless the product's features are identical or equivalent to those described in the specification.


Suppose a patent describes a box with a light source, like an LED, on the top inside to illuminate the box, with only one embodiment provided. The claim is for a box with a light source for illumination.

If a suspected infringing product A has a light source on the side wall, the court is unlikely to uphold infringement because the patent's specification only discloses the light source on the top. Differences in the light source location can be argued to affect the functionality.

Conversely, if product B has an OLED light source on the top, the court may uphold infringement. This is not due to the functional feature but because the OLED is considered equivalent to the LED without changing the effect.


According to Article 4 of the Supreme People's Court Interpretation on Patent Infringement (2010):

“For technical features expressed as functions or effects in claims, the court shall determine the content of such features based on specific implementations and their equivalents described in the Description and Drawings.”

Article 8 of the Supreme People's Court Interpretation (II) (2020) states:

“Functional features refer to technical features defined by their function or effect in the invention, unless the implementation method is clear from the claims alone. If the structure in the infringing product achieving the functional feature is the same or equivalent to the structure described in the patent, it constitutes infringement.”

The court compares the structural features in the specification with those of the suspected infringing product. If they match, it is deemed infringement; if not, it is non-infringement.

This shows a difference in interpreting the scope of functionality in Chinese patent examination practice and judicial practice. During examination, functional features cover all possible structures, while in infringement cases, they only cover structures disclosed in the specification. This discrepancy is most common in EE, pharmacy, and mechanical cases.

While the scope defined by functional features is not always unsupported, there is a relatively low chance of court support.


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