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Navigating the minefield of priority rights

Guoquan Yang and Youping Ma of Bridgeon examine the issues that can arise for applicants who claim a priority right in China and evaluate the requirements for exercising the right effectively

When an applicant overseas would like to file an application in China, he always claims a priority of a first-filed application from his resident country. This is a powerful tool to secure the gap between filing in the applicant's own country and filings in others. With the priority system, most applicants will feel safe disclosing their invention after the first filing of an application.

However, this may be an illusion. A risk is hidden beneath the system. How to claim a priority is a seldom discussed question and therefore few notice the connected issues, which may lead to a disaster difficult to remedy. Unfortunately, this is not a rare case.

Detailed below are three real cases showing how priority affects the validity of a patent. Some information has been omitted or changed for privacy reasons.

First case: priority or unpermitted amendment?

In the first case, an applicant first filed a European patent (EP) invention application. Later, he filed another application in China, which claimed the priority of the EP application. In the latter application, the applicant made a minor amendment. The word "memory" was changed to "semi-conductor memory".

During the examination of the China (CN) application, the examiner found and cited a document published between the priority date and the CN filing date. Then, the examiner issued an office action, in which he held that the CN application could not claim the priority because of the amendment and then used that document to challenge the novelty and inventive step of the CN application.

This was a very difficult office action. In this scenario, if the applicant reverted the CN application back to the original one, it would extend beyond the content as filed, which is not allowed under Chinese practice. If the applicant kept the current CN application, the cited document would destroy its novelty and inventive step.

Finally, this application was rejected.

Second case: priority and patentability

The second case is an invalidity case before the Chinese Patent Re-examination Board. In this case, it was found that the priority application of the CN patent under dispute was disclosed before its CN filing date. In the invalidity petition, the priority of the patent was first challenged since its claims were amended and therefore different from the priority application. Then its own priority document was used to challenge its novelty and inventive step.

Finally, the patent was invalidated.

Third case: foreign priority and domestic priority

The third case is slightly more complex. A US company had a research and development branch in China, which created an invention. In order to acquire quick protection, the US company filed a CN invention application and a CN utility model application simultaneously in China. Five months after the CN filing date, the utility model was granted a patent right. Six months after the CN filing date, the invention application was published. Ten months after the CN filing date, the company made some amendments to the application and filed an application under the Patent Cooperation Treaty (PCT), which claimed the priority of the CN utility model application. One and half years after the CN filing date, the CN invention application was granted and according to Chinese practice, the corresponding CN utility model patent was deemed abandoned. Two years after the CN filing date, the US company took an evaluation of its application and patent and thought that the PCT application would protect the invention in a more detailed manner than the CN invention patent. As a result, it let the CN invention patent lapse without paying the annual fee. By now, it seemed that everything was fine and its intellectual property protection was on the right track.

However, two and half years after the CN filing date, when the PCT application entered the China national phase, an unfavourable situation arose: the PCT application could not claim the priority of the CN utility model application in China and both the CN utility model application and the CN invention application were used to challenge its novelty and inventive step.

How does the priority issue destroy a good patent?

On the surface, the handling of priority in the three cases seemed just a normal routine operation. How could it lead to such bad results?

Given the large number of applications and patents being applied for and granted each year, if the rules applied to the above cases are correct, all similar applications and patents are lying on a dormant volcano which could erupt at any time.

The China Patent Examination Guidelines stipulate that the priority is valid when an application is directed to a subject matter which is the same as the subject matter in the original foreign application

Unfortunately, this is true and these disastrous results were caused by lack of awareness of the priority requirements.

In most situations in China, when an applicant files an application claiming a priority, the patent office will not check the eligibility of the priority. During an examination, an examiner generally assumes the priority is valid and just searches for the prior art documents with respect to the priority date. The examiner only checks whether the pending application relates to a subject matter similar to the priority application and will not go into the specific requirement of the priority.

This might give an applicant the illusion that the priority is just a formality requirement and is easy to handle. Some examiners also hold this opinion. For example, in the second case detailed above, both the collegiate panel of the Patent Re-examination Board and the patentee were surprised by the strategy and combination of the invalidation reasons. Only after the requirement of priority was explained in detail did the collegiate panel start to understand the requirement and make a decision favourable to the invalidation petitioner.

This may be the most unsettling part of this issue. When patentees feel safe about their patent and start to enforce it, it finally comes out in court that the patent is invalid not because it is not a new one but merely because it does not fulfil the priority requirement. This is a disaster for the intellectual property of a patentee, and in most cases, there are no remedies.

What is the requirement for priority?

The China Patent Examination Guidelines stipulate that the priority is valid when an application is directed to a subject matter which is the same as the subject matter in the original foreign application, but do not give a clear explanation about what constitutes the same subject matter.

This is therefore a vague instruction. A lot of practitioners misunderstand this requirement and believe that as long as the subsequent application contains content similar to the original one, it satisfies the priority requirement and is eligible for claiming the priority.

This is not correct. In reality, the requirement for the same subject matter is the same as that for amendment.

As is well known, the requirement for amendment during prosecution in China is very strict. The amendment must be able to be derived directly and unambiguously from the content of the application as filed. In practice, using the same wording as that in the original document as filed is safe for amendment.

The priority right shares very similar stringent requirements to amendment. In the first two cases mentioned above, the applicant and patentee did not realise that the requirement for priority was also very strict when filing the CN applications. Although the main concepts of the subsequent application and patent were similar to the priority application, they did not satisfy the above strict requirement. After first filing, the applicants felt safe to disclose their solutions and their own disclosure became material to be used against their own application and patent. Many now see that, as their own disclosure was very similar to their application and patent, it was very strong evidence against themselves.

Some people would like to argue against the strict requirement by quoting the stipulation regarding verification of priority in the China Patent Examination Guidelines, which states "the phrase 'clearly described' does not mean the manner of illustration is completely identical" (see Section 4.6.2 Chapter 8 Part II of the guidelines). However, following this stipulation in the China Patent Examination Guidelines, it is further explained "if the detailed description of such technical features is described in the application claiming the priority right, and a person skilled in the art cannot directly and unambiguously derive it from the earlier application, the earlier application cannot serve as the basis for claiming the right of priority." If we compare this wording to that in the requirement for amendment, we find that they share the same words, "directly and unambiguously derive from".

Furthermore, if we look into the requirement regarding priority of the Guidelines for Examination in the European Patent Office, we can see a more explicit instruction: "the basic test to determine whether a claim is entitled to the date of a priority document is, as far as the requirement of the 'the same invention' is concerned, the same as the test for determining whether or not an amendment to an application satisfies the requirement of Article 123 (i.e. the requirement for amendment during prosecution)" (see Part F-Chapter VI-5, Section 2.2).

It is clear from the above that if a subsequent application would like to claim the priority of an earlier application, the requirement is not only strict in China but also in Europe and room for amendment is very limited.

A special type of priority: domestic priority in China

Many might query why the PCT application in the third case cannot claim the priority from the CN utility model application in China.

China has ratified the Paris Convention for the Protection of Industrial Property. According to Article 4A(3) and Article 4B of the Paris Convention, the subsequent fate of the earlier application will not affect the validity of the priority. The Paris Convention is valid in China. In this regard, why does the registration of the Chinese utility model patent have an influence on the validity of the priority for the PCT application?

The priority right shares very similar stringent requirements to amendment

The priority stipulated in the Paris Convention only refers to a priority application filed in one country and a subsequent application filed in another country. In China, we call this priority application under the Paris Convention a foreign priority.

In China, a PCT application will be deemed to be an application filed in China, rather than filed in another country, when it enters China. In this regard, both the priority and PCT applications of the third case are deemed as being filed in the same country, i.e. China. This is called domestic priority and is not addressed in the Paris Convention. As a result, the Chinese Patent Office applies some special requirements to it: if the earlier application was already granted at the time of filing the PCT application, the earlier application cannot be taken as a basis of a domestic priority.

Thus, in the third case, since the utility model was granted when the PCT application was filed, it could not serve as a basis for the PCT application. The only way to continue the PCT application was to abandon claiming of the priority and amend the claims to incorporate new subject matter that was not disclosed in the priority utility model application.

How should an applicant handle an application claiming priority?

Priority is a subject regarding matters in a foreign country other than the applicant's own. The experience and knowledge of an applicant drawn from his own country may not be applicable. Sometimes, this can lead to a loss to an application.

For example, an applicant can file a provisional application and then derive a standard one from it in the US. From the perspective of the Chinese Patent Office or European Patent Office, the provisional application and the standard one can sometimes be very different. In this regard, the priority for an application derived from such a provisional one may not be valid in China or Europe.

Many international companies have subsidiaries in China and generate inventions here. Some of these inventions will first be filed in China, which may involve a domestic priority issue as discussed above.

As priority issues can be very complicated, a generic solution is not suitable for every case. Furthermore, most of the actions dealing with priority cannot be reversed. It is therefore extremely important to consult experienced local patent lawyers in advance.

Guoquan Yang
Guoquan Yang is a partner at Bridgeon Law Firm and is a Chinese lawyer and patent attorney. He excels in litigation and has represented clients before the China Supreme Court. With a unique combination of R&D experience, strong expertise in IP disputes and extensive knowledge of US and EP IP practices, he is a trusted advisor to domestic and international clients. Mr Yang is a frequent speaker on intellectual property issues at conferences and forums with judges. He is also a lecturer at the All China Patent Agents Association (ACPAA). He was named as a China Two-Star Patent Litigator.

Youping Ma
Youping Ma is the founding partner of Bridgeon Law Firm and is a Chinese lawyer and patent attorney. With over 15 years of experience, she has worked on many large-scale IP infringement litigations and patent invalidations. She earned her dual degree in computer science and law from Peking University. She is the executive council member of the Capital Intellectual Property Services Association, a standards committee member of the Capital Intellectual Property Services Association and director of the intellectual property committee of the China Productivity Promotion Centre. She was named a Beijing Outstanding Patent Attorney of 2014 and China Four-Star Patent Litigator.

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