[Jian Xu] Make sure you have diverse examples to back up the functional feature in a Chinese patent claim, especially if said functional feature is the inventive point

Patent drafters like functional features (i.e. means-plus-function claims) in patent claims, because they seem to provide a very broad protection scope. Literally, as long as the claimed function is realised, the technical solution falls within the claim. However, in practice, examiners and judges in China tend to treat functional features conservatively, sometime unduly limiting the protection scope. In the balance between protection scope to encourage innovation versus protecting the general interest of the public, the latter is usually given more weight in China.

What then, it the protection scope of a functional feature in patent claims? There are still a great deal of inconsistency across various levels of courts. In practice, many courts would rely on the principle that “patent specification and drawings can be used to interpret claims”, and check what technical means are used to achieve the function. The general consensus now is that the protection scope of functional features in a claim cover the following.

(1) embodiments/examples described in the patent specification

Those embodiments/examples described in the patent specification to achieve the claimed function are within the protection scope.

(2) equivalent features to those embodiments/examples above

The doctrine of equivalence is in play here. The criteria for an equivalent feature is the “basic three”, i.e. basically/substantially the same technical means, basically/substantially the same technical function, and basically/substantially the same technical effect. For example, in a patent claim for protein, minor change of the sequence of amino acids which still achieve substantially the same technical function is deemed as equivalent feature. Note that the latitude for doctrine of equivalence is quite narrow in China.

For prudence, it is safe to assume that the functional features in a patent claim only cover the above two technical solutions, so its protection scope is very much dependant on how many or how diverse the related embodiments are in the patent specification, and how broad a judge might interpret the doctrine of equivalence. The former we can control when drafting the patent. The latter we cannot, and very much depends on the whim of a judge. Therefore, do make sure you have diverse examples to back up the functional feature in a Chinese patent claim, especially if said functional feature is the inventive point.

In principle, there is a third type (3) of technical solution, wherein it employs quite difference technical means yet achieve the same technical function, yet it is obvious for the skilled artisan to think of such technical menas. Clearly this is not within the area of doctrine of equivalence, but still literally falls within the claim of a functional feature. This is a grey area whether this third type of technical solution falls with the scope of a functional feature. In one court case in China, the patent claim contains a functional feature “single-direction penetration”, and the related example in the patent specification is “a cloth with funnel shaped holes”. The defendant also use the “single direction penetration layer”, but such effect is achieved by different technical means “using two layers with one layer being non-woven textiles while the other layer being an absorbent layer”. However, it is obvious for the skilled artisan to think of the two layer approach to achieve said function of “single-direction penetration”. The defendant’s technical solution does not constitute doctrine of equivalence as the technical means are different, however, it is arguably still falls within the scope of the functional feature. In practice, there is great inconsistency whether this type constitutes infringement of a functional feature, particularly given the more weight in protecting public interest. It is safe and prudent not to rely too much on such interpretation.