According to the abstract
In the European patent system, proceedings concerning patent validity can run concurrently in both the European Patent Office (EPO) and a number of national courts. In the UK, a number of cases have addressed the details of how the relationship should be managed between the courts and the EPO when such parallel proceedings are on foot.
Until recently, this had appeared to be settled by rules and guidelines that were logical, if not ideal in all their implications. However, a series of recent cases concerning the revocation and amendment of patents in the EPO have now posed difficult questions for judges at first instance and on appeal.
The solutions have required a significant shift in the UK and EPO relationship and raise awkward questions of their own about the possibility of patents being re-litigated between the same parties. This matters at another level, because the UK experience may inform the relationship between the Unified Patent Court (UPC) and the EPO in similar circumstances.