Just a quick update: On August 28, 2018 the Texas Supreme Court issued yet another set of Amended Rules of Disciplinary Procedure that added a couple of key protections to the investigatory subpoena process for respondent attorneys.
The link to the Order and newly amended rules is here.
Both changes concern a respondent attorney’s right to object to an investigatory subpoena regardless of whether s/he is the subject of that subpoena, and both changes were mandated by the underlying law. See Government Code Section 81.080(b).
It is good news both that the amended rules are now in compliance with the law with respect to this issue and that Texas attorneys caught up in the grievance process have a bit more due process than under the last version of these rules.