I came across a comment in Washington State's version of Rule 4.4 that appears to forbid threatenting to report an undocumented immigrant as a negotiating strategy. It provides in part as follows. Is this provision unique?
"The duty imposed by paragraph (a) of this Rule includes a lawyer's assertion or inquiry about a third person's immigration status when the lawyer's purpose is to intimidate, coerce, or obstruct that person from participating in a civil matter. Issues involving immigration status carry a significant danger of interfering with the proper functioning of the justice system. See Salas v. Hi-Tech Erectors, 168 Wn.2d 664, 230 P.3d 583 (2010). When a lawyer is representing a client in a civil matter, a lawyer's communication to a party or a witness that the lawyer will report that person to immigration authorities, or a lawyer's report of that person to immigration authorities, furthers no substantial purpose of the civil adjudicative system if the lawyer's purpose is to intimidate, coerce, or obstruct that person. A communication in violation of this Rule can also occur by an implied assertion that is the equivalent of an express assertion prohibited by paragraph (a)...."