In G 4/88 the question referred to the Enlarged Board (T 349/89 of 29 April 1988) was whether an opposition instituted before the EPO is transferable only to the opponent's heirs or whether it may be transferred freely either with the opponent's enterprise or with a part of that enterprise operating in a technical field in which the invention to which the patent in suit relates can be exploited. The Enlarge Board examined the situation in which the opposition has been instituted in the interest of the opponent's business or part of that business. The term "business" was understood in a broad sense as describing the an economic activity which is or could be carried on by the opponent and which constituted a specific part of his business assets. In such a situation, the opposition constituted an inseparable part of those business assets. Insofar as those assets were assignable under applicable national laws, the opposition which was part of them had also to be regarded as transferable. The Enlarged Board answered the referred question by stating that an opposition pending before the EPO may be transferred or assigned to a third party as part of the opponent's business assets together with the assets in the interests of which the opposition was filed. Applying G 4/88 to the facts of the case the board in T 349/89 thus held in its decision of 30 November 1989 that the universal successor in title of the original opponent had transferred its opponent status to the singular successor of part of its industrial and commercial activity (operations in the commercial vehicle field) to which the opposition related.

In T 9/00 (OJ 2002, 275) the board found as follows: If, as in the present case, the subject of an opposition is assigned to two different parts of the opponent's company, the status of opponent can pass to a third party only if both parts or the entire company are transferred to it.

In T 298/97 (OJ 2002, 83) the board held that the transfer may be to one, and one only, successor or transferee.

In T 799/97 the opponent had gone bankrupt during the first-instance opposition proceedings. The board held that the opponent's entire business, and so the activities to which the opposition related, had been transferred to the company with which the administrator had concluded a contract of sale. Not all receivables and liabilities had been acquired, but that had not been established as an essential prerequisite for the transfer of opponent status in G 4/88 and T 659/92. In T 384/08 the board confirmed that the mere fact that certain assets were explicitly excluded in an assignment contract was as such not sufficient for concluding that the contract did not result in the transfer of a business or a specific part of it.

In T 423/11 of 11 March 2015 date: 2015-03-11 the board held that the assets transferred were those in the interest of which the opposition had been filed. The objection that not all the corresponding assets had been transferred, because exceptions had been made for some patents, had no bearing. It was true that some patents had not been transferred and only a licence had been given. However, a licence conferred on the licensee the necessary rights to undertake any action to defend the patent under licence. Therefore those exceptions did not deprive the transferee of the general rights conferred on it by the transfer of the other assets.

In T 1421/05 the board held that where the business assets in relation to which an opposition was filed have been transferred and at the same time the transferor has contractually agreed to transfer the opposition to the transferee, the status of opponent remains with the transferor in the absence of there being filed with the Office (a) evidence sufficiently evidencing the transfer and (b) a request to recognise the transfer of opponent status. Where in such a case the transferor subsequently ceases to exist but has a universal successor, the status of opponent is capable of passing to that successor.

In T 2357/12 the board held that in cases of succession by law where parts of an enterprise form new legal entities or are immediately merged with other entities (de-merger, spin-off, secession merger), they would be considered to be cases of universal succession under national (e.g. German) law. The continued existence of the former opponent, and the fact that it would not be possible to decide at first sight to which of the resulting legal entities the part of the enterprise to which the opposed patent was assigned, might result in applying the rules of singular succession under the procedural law of the EPC (see T 136/01, T 1514/06, T 1032/10).

In T 445/16 the board held that, although a spin-off merger ("Umwandlung durch Ausgliederung") was seen as a form of universal succession in German national law, it was, in the context of transfer of opposition status under EPC law, considered to be a transfer of assets within the meaning of G 4/88. See also T 848/13.