A useful post on when joint privilege may apply, with reference to the English High Court decision of R (Ford) v The Financial Services Authority [2011] EWHC 2583 (Admin).

Joint interest privilege arises in cases where two separate parties can claim a joint interest in communications with a particular lawyer, and therefore it can only be waived jointly.

An example of where joint privilege might arise is in the management of a company; where the legal interests of the company and its directors will often coincide or overlap. However, in such scenarios, unless the lawyer is formally retained by both the company and its directors (to advise the directors in their personal capacity) then it does not automatically follow that the directors can claim that any particular communication is subject to joint privilege.

As summarised in the above blog post,

Having regard to the principles in Three Rivers (No 6), the Court also noted that ‘joint privilege should not arise casually or accidentally’. In order to avoid this, the Court laid down a clear test for establishing whether joint privilege could be claimed. The requirements of the test are that the person claiming joint privilege will need to establish that:

• they communicated with the lawyer in question for the purpose of seeking legal advice in their personal capacity;
• they made clear to the lawyer that 
they were seeking legal advice in 
that individual capacity (as opposed merely as representative of a corporation);
• those with whom joint privilege was claimed knew or ought to have appreciated the legal position;
• the lawyer knew or ought to have appreciated that they were communicating with the individual in that individual capacity; and
• the communication with the lawyer 
was confidential.