With over 1000 IPRs and CBMs already filed and PGR eligible patents beginning to issue, can we expect similar growth of PGR filings? The European Patent Office (EPO) Opposition may provide us a bit of a crystal ball regarding what we can expect from PGR. As previously reported in the AIA blog, there are a number of significant differences such as cost, effect on later litigation and anonymity. However, can these really be seen as substantive differences that would lead to different results and trends than we currently see at the EPO. Both procedures assess anticipation (novelty) and obviousness (inventive step). Both procedures take into account formal matters (written description in the United States, added matter in the EPO) and do not allow broadening of patents. Whilst clarity is not a ground of opposition at the EPO, when amended claims are filed during the opposition process they have to satisfy clarity requirements.