Yet More on the Unitary Patent - is there too much prior art?

This moggy had cause to scratch his head about the status of earlier filed but later published national patent applications as prior art against a unitary patent.  He had been alerted by Katfriends Phillips and Leigh that a novelty-destroying prior national right in one country could invalidate the entire unitary patent.  The unitary patent regulation has no conversion provisions.

This is nothing new.  The Community Designs Regulation also has no conversion provisions (perhaps surprisingly, since the Community Trade Mark Regulation does - Articles 108-110), and it is not only possible, it has actually happened that a Registered Community Design has been invalidated on the basis of a prior right in one country only, or less than the whole EU.  So far this has (to the IPKat's knowledge) only been in the case of published trade mark rights (see for example here) and design rights (see for example Decision of Invalidity Division File number: ICD 000000396 here), but it would have been equally possible in the case of an unpublished application for a registered design (as might have been the case in the seminal Pepsico v Grupo Promer case, had the dates been only slightly different).

To expand on the issue, according to Art 54(3) EPC, prior filed but post-published patent applications count as prior art for the purposes of novelty only against a European patent application or European patent.  However, before the EPO, an equivalent national patent application does not count as prior art.  An Examining Division cannot refuse a European patent application , nor an Opposition Division revoke it, on the basis of lack of novelty over an earlier unpublished national patent application.  However, the proprietor may amend the application or patent, if necessary with different claims for that state, to ensure that the patent will be valid for that state.

The problem is that a unitary patent has to have the same claims for all states.  The Regulation states at Article 3:

A European patent granted with different sets of claims for different participating Member States shall not benefit from unitary effect.

So it seems that a prior right in even one country could invalidate the unitary patent in its entirety.  This view is confirmed by Article 65 of the Unified Patents Court Agreement which says:

The Court may revoke a patent, either entirely or partly, only on the grounds referred to in Articles 138(1) and 139(2) of the EPC.

Article 138 mirrors the grounds of opposition, plus extension of protection and lack of entitlement, but Art 139 is the crux - this is the one that allows national rights to be taken into account:

A national patent application and a national patent in a Contracting State shall have with regard to a European patent designating that Contracting State the same prior right effect as if the European patent were a national patent. 

The IPKat is wondering how big a concern this is.  How frequent are prior national rights (as opposed to unpublished prior European applications)?  He also wonders whether anything can be done about it.  He notes that EU member states are required by Article 4 of the Regulation to remove the national effect of a European patent once it has become a unitary patent:

The participating Member States shall take the necessary measures to ensure that, where the unitary effect of a European patent has been registered and extends to their territory, that European patent is deemed not to have taken effect as a national patent in their territory on the date of publication of the mention of the grant in the European Patent Bulletin.

Would it be possible to restore the national effect if the unitary patent was revoked because of prior art that did not exist in a particular country?  Or will the patent proprietor just have to take this risk as part of the cost of the unitary patent?  Merpel in the meantime is still wondering just what the cost of a unitary patent will turn out to be.

As usual, dear readers, over to you.  Is this too much of a risk for patent owners?