Rule 153
Attorney-client evidentiary privilege¹⁶³

(1)¹⁶⁴ Where advice is sought from a professional representative in his capacity as such, all communications between the professional representative and his client or any other person, relating to that purpose and falling under Article 2 of the Regulation on discipline for professional representatives, are permanently privileged from disclosure in proceedings before the European Patent Office, unless such privilege is expressly waived by the client.

(2) Such privilege from disclosure shall apply, in particular, to any communication or document relating to: 

(a) the assessment of the patentability of an invention; 

(b) the preparation or prosecution of a European patent application;  

(c) any opinion relating to the validity, scope of protection or infringement of a European patent or a European patent application.