American Bar Association Model Rules of Professional Conduct - Rule 2.3. Evaluation for Use by Third Persons
(a) A lawyer may provide an evaluation of a matter affecting a client for the use of someone other than the client if the lawyer reasonably believes that making the evaluation is compatible with other aspects of the lawyer's relationship with the client.
(b) When the lawyer knows or reasonably should know that the evaluation is likely to affect the client's interests materially and adversely, the lawyer shall not provide the evaluation unless the client gives informed consent.
(c) Except as disclosure is authorized in connection with a report of an evaluation, information relating to the evaluation is otherwise protected by Rule 1.6.