It is widely accepted that a person who has a privilege may waive it by willingly revealing privileged information to another party. In order to constitute a waiver, the content of the privileged information must be disclosed. Therefore, merely mentioning an expert witness on the witness list may not constitute a waiver of the privilege of the work-product when the name is subsequently removed as a witness.
Partial disclosure of information or content does not inherently mean that the right is waived in respect of all information. For example, disclosure of a written report by an expert does not mean that the privilege of the work product has been waived in respect of evidence identified and views held by an expert not previously reported in the report.
Since the privilege of the work-product protects the rights of both the attorney and the client, each of them may claim it. If a client decides to waive work-product privilege, the attorney shall have no option but and cannot avoid disclosure or have the right to assert the privilege. However, the attorney may prevent the client from waiving the privilege of the opinion work product because of the overriding interest.
There appears to be a discrepancy between the rulings of the District Courts of Appeal as to whether the right needs to be claimed. One court ruled that, unless expressly argued in response to a discovery request, the privilege must be waived. However, the majority of the other courts do not require a timely privilege-based protest as long as it is claimed prior to disclosure. Because there is an unresolved conflict between the courts on this issue, it is recommended that the privilege be asserted as soon as possible.
While voluntary disclosure of a protected matter to a third party usually waives the right, the courts have introduced an exception to this rule when disclosure is made to another litigant who shares a unified interest in the dispute. Under this exception, parties and their lawyers who share a common interest in the dispute can share and exchange information among themselves without charge.
In order to have a shared interest in litigation, all that is required is for the parties to expect litigation against a common adversary on the same issue or issues and to have a clear common interest in sharing the outcome of the trial planning efforts.
To substitute this salutary doctrine with one that is more invasive of privacy rights or restrictive of the discovery process will promote inefficiency, discrimination and dubious activities by those called upon to represent litigants in need of legal assistance. This, in fact, would will the effectiveness of our judicial system and would represent the cause of justice poorly.