Background
The mention of grant was published on 10 December 2024. The patent has two independent claims (product claim 1 and process claim 2) that are not linked by a single general inventive concept. Your client wants full revocation, but currently only has novelty-destroying prior art for claim 1.
Opposition is a central post-grant procedure, but it is governed by strict rules on (i) time limits, (ii) what must be filed in time, and (iii) the extent to which the patent is opposed.
Answers to the statements
a) Notice of opposition must be filed at the latest by 10 September 2025 — True
Under Article 99(1) EPC, notice of opposition must be filed within nine months of publication of the mention of grant.
From 10 Dec 2024, nine months ends on 10 Sep 2025 (same day-number rule for month periods). Therefore statement (a) is true.
b) If opposition is filed against claim 1 only, it can be extended to claim 2 after the opposition period — False
The notice of opposition must state the extent to which the patent is opposed. Once the opposition period has expired, the extent of opposition is generally final and cannot be enlarged (G 9/91), and the Guidelines confirm the opposition division cannot revoke beyond the extent opposed.
So, if you oppose only claim 1, you cannot later “add” claim 2 to the extent after 10 Sep 2025.
Practical consequence: If the client’s objective is revocation of the patent in its entirety, the opposition should be filed against the patent as a whole (extent = 100%), even if the substantiated attack you currently have is only against claim 1.
c) Grounds for opposition must be filed at the latest by 10 November 2025 — False
The EPC does not provide a separate “grounds deadline” after the opposition period. The notice of opposition itself must be a written reasoned statement and must contain the grounds of opposition and an indication of supporting facts and evidence (Rule 76 EPC).
Therefore, all required substantiation must be filed within the 9-month opposition period, i.e. by 10 Sep 2025, not 10 Nov 2025.
(You can file further evidence/arguments later, but admissibility is discretionary and does not change the fact that the opposition must be sufficiently substantiated in time.)
d) Lack of unity is a valid ground for opposition — False
The grounds for opposition are exhaustively listed in Article 100 EPC (e.g. Art. 100(a) novelty/inventive step; 100(b) sufficiency; 100(c) added matter). Lack of unity is not among them, and the Enlarged Board confirmed in G 1/91 that unity is irrelevant in opposition.
Exam Tip:
- Always separate extent from grounds: if you want full revocation, oppose the patent as a whole (extent), even if you currently only have a strong attack on one claim.
- Remember the “one package” nature of the notice: opposition = notice + fee + substantiated grounds within 9 months (Art. 99(1) + Rule 76).
- Don’t try “unity” in opposition: it’s a search/examination concept, not an Art. 100 ground (G 1/91).
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.