The attorney client privilege is sacrosanct, no?  Well, not really.  Heth v Satterlee Stephens Burke & Burke LLP  2019 NY Slip Op 30555(U)  March 5, 2019  Supreme Court, New York County  Docket Number: 650379/2015  Judge: Andrew Borrok demonstrates what happens when the client possibly  discusses how attorney 1 is handling the case with attorney 2.

“As more fully set forth on the record, the “at-issue” waiver of the attorney-client privilege arises
where a party places the subject matter of privileged communications at issue, thereby making
invasion of the privilege necessary to assess the validity of a claim or defense, and where the
opposing party would be deprived of critical information absent a waiver of privilege (Deutsche
Bank Trust Co. of Ams. v Tri-Links Inv. Trust, 43 AD3d 56, 63 [1st Dept 2007]). In the context
of a legal malpractice action involving concurrent representation by the defendant and non-party
counsel in the same underlying litigation or transaction, New York courts have consistently
found that the privilege is waived with respect to communications with the non-party counsel
concerning the litigation or transaction (Goetz v Volpe, 11 Misc3d 632, 635 [Sup Ct, NY County 2006]). In such cases, communications with non-party counsel in connection with the
underlying action lose their privilege to the extent that they are relevant in establishing whether
the plaintiff relied on the advice of the non-party counsel and whether the plaintiff was harmed
as a result (IMO Indus., Inc. v Anderson Kill & Glick, P.C., 192 Misc2d 605, 609, 611 [Sup Ct,
New York County 2002]). ”

“Specifically, the disclosure of the communications between Messrs. Heth and Mellen is essential
to SSBB and Mr. Markham’s defense that any alleged reliance by Mr. Heth on legal advice
provided by SSBB and Mr. Markham did not proximately cause Mr. Beth’s alleged damages
(i.e., the theory being that Mr. Mellen provided deficient legal advice rather than SSBB and Mr.
Markham [or potentially, also provided deficient advice]). This disclosure is also critical to
SSBB’s and Mr. Markham’s defense that it was Mr. Mellen, not SSBB and Mr. Markham, who
represented Mr. Heth with respect to the March and December agreements, that Mr. Heth was
aware that any release from the March agreement needed to be in writing, and to defend against
the allegation that SSBB and Mr. Markham suppressed information from Mr. Heth regarding the
agreements. “