A non-party deponent, served with a subpoena, arrives for a deposition.  That non-party  wisely brings an attorney.  What may the attorney do at the deposition?  It depends where the case is taking place.  In the 4th Department (22 Counties, roughly half the state?) the attorney will be permitted no objections and may not speak.  Sciara v Surgical Assoc. of W. N.Y., P.C.   2013 NY Slip Op 01741  Released on March 15, 2013   Appellate Division, Fourth Department  hews to the line first set in Thompson v. Mather, 70 AD3d 1436 (4th Dept., 2010).

"As we stated in Thompson, "counsel for a nonparty witness does not have a right to object during or otherwise to participate in a pretrial deposition. CPLR 3113 (c) provides that the examination and cross-examination of deposition witnesses shall proceed as permitted in the trial of actions in open court’ " (id. [emphasis added]), and it is axiomatic that counsel for a nonparty witness is not permitted to object or otherwise participate in a trial (see e.g. id.). We recognize that 22 NYCRR 221.2 and 221.3 may be viewed as being in conflict with CPLR 3113 (c) inasmuch as sections 221.2 and 221.3 provide that an "attorney" may not interrupt a deposition except in specified circumstances. Nevertheless, it is well established that, in the event of a conflict between a statute and a regulation, the statute controls (see Matter of Hellner v Board of Educ. of Wilson Cent. School Dist., 78 AD3d 1649, 1651).

We also recognize the practical difficulties that may arise in connection with a nonparty deposition, which also have been the subject of legal commentaries (see e.g. 232 Siegel’s Practice Review, Objections by Nonparty Witness? at 4 [Apr. 2011]; Patrick M. Connors, Supp Practice Commentaries, McKinney’s Cons Laws of NY, Book 7B, CPLR 3313:7, 2013 Pocket Part at 31-33). However, we decline to depart from our conclusion in Thompson (70 AD3d at 1438) that the express language of CPLR 3113 (c) prohibits the participation of the attorney for a nonparty witness during the deposition of his or her client. We further note, however, that the nonparty has the right to seek a protective order (see CPLR 3103 [a]), if necessary. "

A lively dissenting opinion (2 judges) ensures that we will see this case in the Court of Appeals.