Legal framework
A European patent application may be filed by reference to a previously filed application. For the purposes of obtaining a filing date, the documents filed must contain an indication that a European patent is sought, information identifying or contacting the applicant, and either a description or a reference to a previously filed application: Article 80 EPC and Rule 40(1) EPC.
Where the application is filed by reference, the reference must contain the filing date, the filing number and the office with which the previous application was filed, and must indicate that the reference replaces the description and any drawings: Rule 40(2) EPC, Guidelines A-II, 4.1.3.1.
A certified copy of the previously filed application must be supplied within two months of the filing date unless the application is already available to the EPO under the conditions laid down by the President. For a Chinese national application, that exception does not apply in this context; the Guidelines state that, apart from Euro-direct applications and international applications filed with the EPO as receiving Office, a certified copy must be filed: Rule 40(3) EPC, Guidelines A-II, 4.1.3.1.
For priority, PCT Article 8(1) allows an international application to claim priority from an earlier application filed in or for a Paris Convention country. The conditions and effect of the priority claim are governed by Article 4 of the Paris Convention: PCT Article 8(2)(a).
A later application for the same subject-matter can only be treated as the “first application” in the limited situation of Paris Convention Article 4C(4): the earlier application must have been withdrawn, abandoned or refused, without being laid open to public inspection, without leaving rights outstanding, and without having served as a basis for claiming priority. The EPO Guidelines express the same rule in F-VI, 1.4.1.
Statement a)
False.
The reference to CN-A cannot include only the filing number.
Under Rule 40(2) EPC, a reference to a previously filed application must state the filing date, the filing number and the office with which the application was filed. It must also indicate that the reference replaces the description and any drawings. The EPO Guidelines confirm these requirements in A-II, 4.1.3.1.
Therefore, merely giving the filing number of CN-A is not enough.
Statement b)
True.
Because EP-A was filed by reference to CN-A, the applicant must provide a certified copy of CN-A to the EPO under Rule 40(3) EPC.
The Guidelines explain that a certified copy is dispensed with only where the referenced application is already available to the EPO under the conditions specified by the President. For filing by reference, the listed exceptions are Euro-direct applications and international applications filed with the EPO as receiving Office. In all other cases, a certified copy must be filed: Guidelines A-II, 4.1.3.1.
Since CN-A is a Chinese national application, the applicant must supply the certified copy. Since CN-A is not in an EPO official language, a translation into English, French or German would also be required under Rule 40(3) EPC.
Statement c)
True.
The Chinese application corresponding to PCT-A would lack novelty, assuming it claims the same subject-matter as CN-A.
CN-A was the true first filing for the invention, filed on 5 February 2024. EP-A was filed later, on 7 August 2025, for the same subject-matter by reference to CN-A. EP-A cannot be treated as a new first application under Paris Convention Article 4C(4), because CN-A had already been published on 16 July 2025 and was not filed in or for the same state as EP-A.
Therefore, PCT-A cannot validly claim priority from EP-A for that subject-matter. Its effective date would be its own international filing date. CN-A was already published before that date and therefore forms prior art.
Under Chinese patent law, novelty requires that the invention does not form part of the prior art, and “prior art” means technology known to the public in China or abroad before the filing date.
Thus, the publication of CN-A would destroy novelty of the Chinese application corresponding to PCT-A.
Statement d)
True.
The European application corresponding to PCT-A would also lack novelty.
For the same reasons as for statement c), PCT-A cannot validly claim priority from EP-A. CN-A was published on 16 July 2025, before PCT-A’s effective filing date. It therefore forms part of the state of the art for the European application corresponding to PCT-A under Article 54(2) EPC, which includes everything made available to the public before the filing date.
Since CN-A discloses the same subject-matter, it is novelty-destroying for the European application corresponding to PCT-A.
Exam tip
Be careful with attempts to “restart” the priority year. A later application can replace an earlier first application as the priority basis only in the narrow situation of Paris Convention Article 4C(4). If the earlier application was published, or if the later application was not filed in or for the same state, the later application is not a new “first application”. Here, EP-A has a filing date for EPO purposes, but it cannot create a valid priority right over CN-A for the same invention.
Legal Disclaimer
The information provided in this post is for general informational purposes only and does not constitute legal advice. This content should not be used as a substitute for professional legal advice tailored to your specific circumstances. For advice related to any specific legal matters, you should consult a qualified attorney.