As best as I can determine, the answer to this question hinges upon which courts Elizabeth Warren represented clients in front of and how she obtained these clients.
Here are the facts as I understand it. She has never been admitted to practice in Massachusetts, that seems clear. At various times she has been admitted in Texas and until a few weeks ago New Jersey. This would allow her to practice law in state courts located in those two states even if she did not reside in those states (although some states require you to maintain an office in the state in order to practice there, Texas does not and these laws are often subject to challange).
She can also practice law in any federal court to which she has been admitted to practice. Generally in order to appear in a federal court you must either move to be allowed to appear pro hoc for a particular matter or be a member of good standing of the state where the federal court is located in which you seek to appear and then gain admission to that court. Where it gets tricky is there are loopholes and exceptions to this rule.
Now to the extent that the charge is that she engaged in the unauthorized practice of law in Massachusetts by appearing in federal courts elsewhere while located in Massachusetts , I find her not gulity based on these exceptions . One such exception is that simply preparing legal briefs in non-Massachusetts federal cases or providing advice on federal law while located in Massachusetts and maintaining a primary office in Massachusetts does not by itself constitute the "systamatic and continuous practice of law" in Massachusetts that would be prohibited, particularly when the cases involve matters of federal law only such as bankruptcy. While there may be outlier cases that dispute this, most of the cases cited in the various blogs that have discused this issue seem to support that argument. See for example Sperry v. Florida (1963) which clarified that the federal government can independently regulate who practices before it and states cannot enjoin such practice within their borders as the unauthorized practice of law. Various military JAG agencies and nearly all federal agencies will accept applicants licensed in any U.S. jurisdiction for attorney positions, regardless of the state/territory jurisdiction where the position is actually located. Because Warren limited her private practice to bankruptcy and the Constitution expressly guarantees federal authority over bankruptcy law, she's protected under the Supremacy Clause. The argument is also supported by
Massachusetts Rule of Professional Conduct 5.5(d), which states that:
“A lawyer admitted in another United States jurisdiction, and not disbarred or suspended from practice in any jurisdiction, may provide legal services in this jurisdiction that…are services that the lawyer is authorized to provide by federal law or other law of this jurisdiction.”
The Official Comments to Rule 5.5(d) further elaborate to make explicit that 5.5(d) permits such an attorney to have even a “systematic and continuous presence in [Massachusetts] for the practice of law as well as provide legal services on a temporary basis.”
Thus as long as the cases in which she appeared in are entirely cases from the federal courts dealing with federal law , and indeed appear to be cases lying even outside the jurisdiction of the Massachusetts federal courts, the Massachusetts Rules of Professional Conduct appear to explicitly exempt Professor Warren’s actions in those cases from the prohibitions on the unauthorized practice of law.
However, Professor Jacobson also argues that Ms. Warren may have violated a prohibition on communications advertising legal services to prospective clients in Massachusetts by lawyers who are only admittied to practice in other jurisdictions. The question raised is whether listing the location of one's Massachusetts office in an official court filing in which one is otherwise properly authorized to appear can be properly construed as a communication advertising legal services to prospective clients in Massachusetts. Jacobson does not cite to any cases which support his view that asserts that an official court filing may constitute an “advertisement for legal services” merely because it lists the attorney’s Massachusetts office address. I would be very surprised if there were any since such an argument does not make much sense. Being a professor at a law school and listing your office address on a pleading would hardly make one think that you were running a full scale law practice out of your Harvard Law School office.
Jacobson claims that Warren was in fact doing just that, representing dozens of clients and earning huge fees all while running an office out of Harvard Law School despite never being admittied into Massachusetts. If in fact, Warren did exactly that, she might be in serious trouble as it could then be alleged that she maintained an office in which she was engaged in the systamatic and contunious practice of law in a state within in which she was not authorized to practice. That would violate the Massachusetts Rules of Professional Conduct. The problem is that the good professor is rather light on any actual facts let alone names and dates of cases wherein Ms. Warren allegedly did this. He mentions a few federal or Supreme Court cases but again these would seem to be covered by the loophole discussed above.
Activity by Warren that is not “systematic and continuous” would inherently seem to fit within Rule 5.5′s broad and vague category of permissible “temporary” activity, which official comment 6 states may even include “services in this jurisdiction on a recurring basis, or for an extended period of time, as when the lawyer is representing a client in a single lengthy negotiation or litigation.” Unfortunately, the phrase “systematic and continuous” is undefined but it seems clear that it means holding oneself out to the public in a manner that the public might interpret as a claim to being admitted to practice in Massachusetts. The emphasis in these type of rules is always on how an attorney holds herself out to the general public and potential clients.
To the extent Warren actively marketed her services in Massachusetts , she would thus have a clear problem but there is no evidence she did so. Rather it appears as if she simply accepted work from out of state clients in matters already pending in out of state federal courts that dealt with bankruptcy and other areas of exclusively federal law. Based on the facts as we know them, it’s difficult to argue that she was engaged in the “systematic and continuous” practice of law in Massachusetts. But that could change if we learn more about her cases and how she obtained her clients.