In a panel discussion on the case-law of the EPO boards of appeal two weeks ago here in Munich, some poeple including Rudolf Teschemacher (former chairman of an EPO Board of Appeal) have noted that interestingly, experience has shown that the total number of appeals filed against granted patents decreases when the delay for filing oppositions is increased.
This somewhat counter-intuitive relation may be explained by the fact that the majority of oppositions is filed for precautionary reasons such that the longer the delay for filing the opposition, the bigger the fraction of cases where an appeal turns out to be unneccessary.
Looking at the German nullity procedure, there are practically no nullity suits filed as a "precautionary measure" but in almost every case there is a parallel infringement action pending. This may be due to the high costs of the nullity procedure on the one hand but also due to the lack of time pressure.
This means that a prolongation of the 9-months term for filing an opposition would reduce the total number of appeals and would concentrate the appeal procedure to cases of high economical importance.
Following this thought to the extreme would correspond to a prolongation of the delay for filing an opposition at the EPO up to 20 years from the filing date. The result would be a central revocation instance at the EPO realizing one of the two aims of the "European and EU Patent Court Agreement" project recently rejected by the European Court of Justice.
One of the interesting aspects of this idea is that the time limit for filing the opposition may be amended by the administrative council (Art. 33(1)a EPC) with a majority of three quarters (Art. 35(2) EPC) and thus in a very simple way.