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
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
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
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
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
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
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,
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
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
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
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
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 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 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 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