A written reasoned statement of the grounds for opposition must be filed within the opposition period.[Art. 99(1); Rule 76(1); ]

Opposition may only be filed on the grounds that:[Art. 100; ]

(i)the subject-matter of the European patent is not patentable under Art. 52 to Art. 57, because it[Art. 100(a); ]

(ii)the European patent does not disclose the invention in a manner sufficiently clear and complete for it to be carried out by a person skilled in the art (see Art. 83);[Art. 100(b); ]

(iii)the subject-matter of the European patent extends beyond the content of the application as filed (see Art. 123(2)) or, if the patent was granted on a divisional application or on a new application filed under Art. 61 (new application in respect of the invention by the person adjudged in a final decision to be entitled to the grant of a European patent), beyond the content of the earlier application as filed (see Art. 76(1)).[Art. 100(c); ]

(See also D‑V, 3, D-V, 4 and D-V, 6, and C‑IV).

Note that each single condition mentioned above forms an individual legal basis for objection to the maintenance of the patent. Consequently, each such condition is to be regarded as a separate ground for opposition (see G 1/95 and G 7/95).

The following allegations, for example, do not constitute grounds for opposition: that national rights of earlier date exist which put the patentability of the invention in question (see, however, H‑III, 4.4), that the patent proprietor is not entitled to the European patent, that the subject-matter of the patent lacks unity, that the claims are not supported by the description (unless it is also argued that the claims are so broadly worded that the description in the specification does not sufficiently disclose the subject-matter within the meaning of Art. 100(b)), that the form and content of the description or drawings of the patent do not comply with the provisions as to formal requirements as set forth in Rules 42 and Rule 46, or that the designation of the inventor is incorrect. Nor does the simple allegation that priority has been wrongly claimed constitute a ground for opposition. However, the matter of priority must be subjected to a substantial examination in the course of opposition proceedings if prior art is invoked in connection with a ground for opposition under Art. 100(a) in relation to which the priority date is of decisive importance (see G‑IV, 3, and F‑VI, 2).