The following deficiencies fall into this category:

Accordingly, the opposition is deficient if, for example, notice of opposition is submitted to the EPO belatedly, i.e. after expiry of the nine-month period, or where the opposition is notified within the opposition period but only verbally in a telephone call officially noted in the files. This category of deficiency also includes oppositions which, notwithstanding Art. 99(1), are filed with the central industrial property office of a contracting state or an authority thereunder and not forwarded by these offices either at all or in time for them to be received by the EPO before the expiry of the opposition period. There is no legal obligation upon these offices or authorities to forward oppositions to the EPO.

Such a deficiency exists if the EPO is unable to identify the relevant patent on the basis of the particulars in the notice of opposition; for example, if only the proprietor of the contested patent and perhaps the title of the invention for which the patent was granted are mentioned in the notice of opposition. Such particulars alone are not an adequate description of the contested European patent, unless the patent proprietor who alone is named possesses only one patent or possesses several patents, the subject-matter of only one of which fits the title of the invention given in the notice of opposition, being clearly distinct from the subject-matter of the other patents which this proprietor holds. A mere indication of the number of the contested European patent in the notice of opposition constitutes sufficient identification of the patent concerned, provided that no conflicting information is given, e.g. an inconsistent name for the patent proprietor, and the conflict cannot be resolved from the information given.

(iii)the notice of opposition contains no statement of the extent to which the European patent is opposed; [Rule 76(2)(c); ]

Such a deficiency is present if it is not clear from the requisite statement whether the opposition is directed against the entire subject-matter of the patent or only a part of it, i.e. whether it is directed against all the claims or only against one or a part of one claim, such as an alternative or embodiment;

(iv)the notice of opposition contains no statement of the grounds on which the opposition is based; [Rule 76(2)(c); ]

A notice of opposition contains such a deficiency if it does not mention at least one of the grounds for opposition referred to in Art. 100 (see D‑III, 5). If non-patentability is given as a ground for opposition, the statement of grounds must at least implicitly indicate which conditions for patentability (Art. 52 to Art. 57) are considered not to have been fulfilled.

(v)the notice of opposition is not adequately substantiated; [Art. 99(1); Rule 76(2)(c); ]

According to Rule 76(2)(c), a notice of opposition has to contain a statement of the extent to which the European patent is opposed, the grounds on which the opposition is based, as well as an indication of the facts and evidence presented in support of these grounds for opposition.

The wording of Rule 76(2)(c) clearly indicates that there is a difference between the grounds for opposition, i.e. the legal basis for revocation of the patent (e.g. Art. 100(a)), and the facts and evidence presented in support of these grounds. Where the facts and evidence are entirely absent or so vague as not to allow a proper understanding of the case, the opposition is considered to contain only a mere allegation, which is not sufficient to render the opposition admissible.

Therefore, the opponent has to substantiate the grounds for opposition by adducing facts, evidence and arguments for at least one of those grounds. The opponent has to establish the legal and factual framework on which the opposition rests to pave the way for a substantive assessment. As a consequence, the division and the patent proprietor need to be able to understand, without further investigation of their own, the issues that need to be decided. It is not necessary for the admissibility of the opposition that a final decision can be taken without further investigation. In other words, it is not a question of admissibility but of substantive examination whether the facts on which the opponent relies in comprehensibly explaining a ground for opposition are or can be proven. Where the grounds comprise an allegation of a prior use or an oral disclosure prior to the date of filing or the priority date, the opposition division must be supplied with an indication of the facts, evidence and arguments necessary to determine

Where there are multiple grounds for opposition, if the facts, evidence and arguments for one ground are sufficiently indicated, the opposition is admissible even if the facts, evidence and arguments in support of the other grounds are submitted belatedly. Such belated facts, evidence and arguments are in that event dealt with in accordance with E‑VI, 2. Owing to the length of the opposition period (nine months), however, in order to expedite the opposition proceedings it is recommended that a single copy of any written evidence indicated in the notice of opposition be submitted as soon as possible and ideally with the notice of opposition.

Otherwise, if the opposition is admissible, the opponent will be invited to supply such evidence as soon as possible and as a rule within two months. If the documents thus requested are neither enclosed nor filed within the time limit set, the opposition division may decide not to take into account any arguments based on them. (As regards facts or evidence not submitted in due time and arguments presented at a late stage see E‑VI, 2, and E‑III, 8.6.)[Rule 76(2)(c); Rule 83; ]

As far as the admissibility of an opposition is concerned, it is immaterial whether and to what extent the facts, evidence and arguments submitted in due time actually warrant revocation of the contested European patent or its maintenance in amended form. On the one hand, an unconvincing ground for opposition may have been substantiated (making the opposition admissible), whereas on the other hand a deficient submission may have been rejected as inadmissible even though, if properly drafted, it could have succeeded (see also T 222/85).

The substantiation of the grounds for opposition thus has to be clearly distinguished from the actual assessment of the evidence, which is part of the process of ascertaining whether the opposition is well-founded in substance, i.e. proven. Subject to the admissibility of the opposition, this has to be established by the opposition division in the light of the applicable standard of proof (G‑IV, 7.5.2).

(vi)the opposition does not indicate beyond any doubt the identity of the person filing the opposition (Art. 99(1) and Rule 76(2)(a)).[Art. 99(1); Rule 76(2)(a); ]