Why interpretation of technical terms in patent claims matters – part two

Last week we discussed why interpretation of technical terms in patent claims matters. In the invalidity procedure relating to Chinese patent ZL200780042463.2, the petitioner raised the ambiguity of the meaning of “the length of the burrs”. The patentee rebutted that, as clearly defined in the description, ‘burr’ refers to the “seeped burr”, which oozes through the gaps between the upper and lower dyes of the mould, rather than the “slit burr”, which flows inside the slits.

The collegiate panel of the China National Intellectual Property Administration (CNIPA) opined that clear expression of claims is vital in ascertaining the scope of protection of the patent at issue. A claim is devoid of clarity if a person skilled in the art does not have a clear and explicit understanding of the meaning of the terms used in a claim based on the text of the description and it thus becomes impossible to determine the scope of protection.

Regarding the length of burrs, Paragraph 0072 of the description fails to unequivocally acknowledge that the burr mentioned in the patent at issue refers to the seeped burr leaking through the gaps between the upper and lower dyes of the mould, as argued by the patentee, rather than the slit burr flowing inside the six slits. Paragraphs 0139 and 0140 of the description describe the burr as the cured portion that flows along the slits, rather than that seeping through the gap between the upper and lower dyes, as interpreted by the patentee. There are two portions in Figure 5 marked as 410. In Figure 5(b), the extended cured portion is obviously not the burr inside the six slits of the lower dye, but that formed between the fitting surface of the upper and lower dyes – this is likely the seeped burr alleged by the patentee.

As for the 410 marked in Figure 5(a), it would also be impossible for a person skilled in the art to ascertain without doubt that:

• the 410 here corresponds to the 410 shown in Figure 5(b), or
• the 410 here refers to the burrs inside the six slits of the lower dye.

The collegiate panel therefore concluded that the statement and definition of the length of burrs in the description lacked clarity and that a person skilled in the art cannot clearly and explicitly ascertain whether the length of burrs in claim 1 refers to those in the six slits of the lower dye or that of the seeped burr between the fitting surface of the upper and lower dyes as alleged by the patentee. The collegiate panel thus concluded that the scope of protection of claim 1 was not clear.

The CNIPA issued a ruling in invalidity decision 53229 invalidating the invention patent.

The patentee later withdrew the civil infringement suit.

Comment

The reason for the patentee’s inconsistent interpretation of the claims could be ascribed to the parallel infringement proceeding. Since claims are to be interpreted in accordance with the text of the description, the alleged infringing product will not fall into the scope of protection of the patent at issue. The patentee saw an opportunity in one marking of the drawing that might serve as a basis for an alternative interpretation and eventually led to the conclusion that the alleged infringing product fell into the scope of protection of the patent at issue.

Given that two of the aforesaid prior art relate to the patentee, the patentee must be well-versed regarding the meaning of the length of burrs in prior art. In the absence of explicit disclosure on any difference between the meaning of the length of burrs in the description of the patent at issue and that of prior art, it is evidently inadvisable to opt for a different interpretation of the term.

The invalidation of the patent at issue is an example of a patentee shooting themselves in the foot rather than a drafting misstep. If the patentee had stuck to the same interpretation of the length of burrs adopted by the prior art, the meaning would have been unequivocal. Even if the reference numeral 410 is marked between two slits, the burrs may be distributed along the whole periphery, not just on the mark of 410. In light of the greater gaps within the six slits, there will be more burrs inside the slits than between the slits and thus the maximum length of burrs will occur inside the slit. Since the length of burrs refers to their maximum length, which are denoted as 410, the meaning of the length of burrs will be consistent with the prior art.

It is highly likely that the invalidation of the patent at issue is the immediate consequence of the patentee’s arbitrary post-grant interpretation of the scope of protection, which is specifically prohibited by the Patent Law. The essence of the law is that the patentee exchanges voluntary disclosure for protection. If the patentee were to be allowed to broaden the scope of protection at will, this would result in the abuse of the patent right and thus be detrimental to the interests of the stakeholders and the public.

The case is a useful reminder that patentees need to tread carefully when exercising their rights to avoid any abuse.