In G 2/04 the Enlarged Board also considered the issue of what could be done if there was a justifiable legal uncertainty as to how the law was to be interpreted in respect of the question of who the correct party to the proceedings is. It decided that in such a situation it was legitimate that the appeal was filed in the name of the person whom the person acting considers, according to his interpretation, to be the correct party, and at the same time, as an auxiliary request, in the name of a different person who might, according to another possible interpretation, also be considered the correct party to the proceedings.

For an example of a case where a justifiable legal uncertainty as to the person entitled to appeal existed, see T 1091/02 of 28 June 2006 date: 2006-06-28.