Massachusetts Rules of Professional Conduct Rule 1.10: Imputed Disqualification: General Rule
(a) While lawyers are associated in a firm, none of them shall knowingly represent a client when any one of them practicing alone would be prohibited from doing so by Rule 1.7, 1.8(c), or 1.9. A lawyer employed by the Public Counsel Division of the Committee for Public Counsel Services and a lawyer assigned to represent clients by the Private Counsel Division of that Committee are not considered to be associated. Lawyers are not considered to be associated merely because they have each individually been assigned to represent clients by the Committee for Public Counsel Services through its Private Counsel Division.
(b) When a lawyer has terminated an association with a firm, the firm is not prohibited from thereafter representing a person with interests materially adverse to those of a client represented by the formerly associated lawyer and not currently represented by the firm, unless:
(1) the matter is the same or substantially related to that in which the formerly associated lawyer represented the client; and
(c) A disqualification prescribed by this rule may be waived by the affected client under the conditions stated in Rule 1.7.
(d) When a lawyer becomes associated with a firm, the firm may not undertake to or continue to represent a person in a matter that the firm knows or reasonably should know is the same or substantially related to a matter in which the newly associated lawyer (the "personally disqualified lawyer"), or a firm with which that lawyer was associated, had previously represented a client whose interests are materially adverse to that person unless:
(2) the personally disqualified lawyer (i) had neither substantial involvement nor substantial material information relating to the matter and (ii) is screened from any participation in the matter in accordance with paragraph (e) of this Rule and is apportioned no part of the fee therefrom.
(1) all material information which the personally disqualified lawyer has has been isolated from the firm;
(2) the personally disqualified lawyer has been isolated from all contact with the client relating to the matter, and any witness for or against the client;
(3) the personally disqualified lawyer and the firm have been precluded from discussing the matter with each other;
(4) the former client of the personally disqualified lawyer or of the firm with which the personally disqualified lawyer was associated receives notice of the conflict and an affidavit of the personally disqualified lawyer and the firm describing the procedures being used effectively to screen the personally disqualified lawyer, and attesting that (i) the personally disqualified lawyer will not participate in the matter and will not discuss the matter or the representation with any other lawyer or employee of his or her current firm, (ii) no material information was transmitted by the personally disqualified lawyer before implementation of the screening procedures and notice to the former client; and (iii) during the period of the lawyer's personal disqualification those lawyers or employees who do participate in the matter will be apprised that the personally disqualified lawyer is screened from participating in or discussing the matter; and
(5) the personally disqualified lawyer and the firm with which he is associated reasonably believe that the steps taken to accomplish the screening of material information are likely to be effective in preventing material information from being disclosed to the firm and its client.
In any matter in which the former client and the person being represented by the firm with which the personally disqualified lawyer is associated are not before a tribunal, the firm, the personally disqualified lawyer, or the former client may seek judicial review in a court of general jurisdiction of the screening procedures used, or may seek court supervision to ensure that implementation of the screening procedures has occurred and that effective actual compliance has been achieved.
Adopted June 9, 1997, effective January 1, 1998.
Definition of "Firm"
 For purposes of the Rules of Professional Conduct, the term "firm" includes lawyers in a private firm, and lawyers in the legal department of a corporation or other organization, or in a legal services organization. Whether two or more lawyers constitute a firm within this definition can depend on the specific facts. For example, two practitioners who share office space and occasionally consult or assist each other ordinarily would not be regarded as constituting a firm. However, if they present themselves to the public in a way suggesting that they are a firm or conduct themselves as a firm, they should be regarded as a firm for the purposes of the Rules. The terms of any formal agreement between associated lawyers are relevant in determining whether they are a firm, as is the fact that they have mutual access to information concerning the clients they serve. Furthermore, it is relevant in doubtful cases to consider the underlying purpose of the Rule that is involved. A group of lawyers could be regarded as a firm for purposes of the rule that the same lawyer should not represent opposing parties in litigation, while it might not be so regarded for purposes of the rule that information acquired by one lawyer is attributed to the other.
 With respect to the law department of an organization, there is ordinarily no question that the members of the department constitute a firm within the meaning of the Rules of Professional Conduct. However, there can be uncertainty as to the identity of the client. For example, it may not be clear whether the law department of a corporation represents a subsidiary or an affiliated corporation, as well as the corporation by which the members of the department are directly employed. A similar question can arise concerning an unincorporated association and its local affiliates.
 Similar questions can also arise with respect to lawyers in legal aid. Lawyers employed in the same unit of a legal service organization constitute a firm, but not necessarily those employed in separate units. As in the case of independent practitioners, whether the lawyers should be treated as associated with each other can depend on the particular rule that is involved, and on the specific facts of the situation.
 Where a lawyer has joined a private firm after having represented the government, the situation is governed by Rule 1.11 (a) and (b); where a lawyer represents the government after having served private clients, the situation is governed by Rule 1.11(c)(1). The individual lawyer involved is bound by the Rules generally, including Rules 1.6, 1.7 and 1.9.
Principles of Imputed Disqualification
 The rule of imputed disqualification stated in paragraph (a) gives effect to the principle of loyalty to the client as it applies to lawyers who practice in a law firm. Such situations can be considered from the premise that a firm of lawyers is essentially one lawyer for purposes of the rules governing loyalty to the client, or from the premise that each lawyer is vicariously bound by the obligation of loyalty owed by each lawyer with whom the lawyer is associated. Paragraph (a) operates only among the lawyers currently associated in a firm. When a lawyer moves from one firm to another, the situation is governed by Rules 1.9(b) and 1.10(b), (d) and (e).
 Rule 1.10(b) operates to permit a law firm, under certain circumstances, to represent a person with interests directly adverse to those of a client represented by a lawyer who formerly was associated with the firm. The Rule applies regardless of when the formerly associated lawyer represented the client. However, the law firm may not represent a person with interests adverse to those of a present client of the firm, which would violate Rule 1.7. Moreover, the firm may not represent the person where the matter is the same or substantially related to that in which the formerly associated lawyer represented the client and any other lawyer currently in the firm has material information protected by Rules 1.6 and 1.9(c).
 Paragraphs (d) and (e) of Rule 1.10 are new. They apply when a lawyer moves from a private firm to another firm and are intended to create procedures similar in some cases to those under Rule 1.11(b) for lawyers moving from a government agency to a private firm. Paragraphs (d) and (e) of Rule 1.10, unlike the provisions of Rule 1.11, do not permit a firm, without the consent of the former client of the disqualified lawyer or of the disqualified lawyer's firm, to handle a matter with respect to which the disqualified lawyer was personally and substantially involved, or had substantial material information, as noted in Comment 11 below. Like Rule 1.11, however, Rule 1.10(d) can only apply if the lawyer no longer represents the client of the former firm after the lawyer arrives at the lawyer's new firm.
 If the lawyer has no confidential information about the representation of the former client, the new firm is not disqualified and no screening procedures are required. This would ordinarily be the case if the lawyer did no work on the matter and the matter was not the subject of discussion with the lawyer generally, for example at firm or working group meetings. The lawyer must search his or her files and recollections carefully to determine whether he or she has confidential information. The fact that the lawyer does not immediately remember any details of the former client's representation does not mean that he or she does not in fact possess confidential information material to the matter.
 If the lawyer does have material information about the representation of the client of his former firm, the firm with which he or she is associated may represent a client with interests adverse to the former client of the newly associated lawyer only if the personally disqualified lawyer had no substantial involvement with the matter or substantial material information about the matter, the personally disqualified lawyer is apportioned no part of the fee, and all of the screening procedures are followed, including the requirement that the personally disqualified lawyer and the new firm reasonably believe that the screening procedures will be effective. For example, in a very small firm, it may be difficult to keep information screened. On the other hand, screening procedures are more likely to be successful if the personally disqualified lawyer practices in a different office of the firm from those handling the matter from which the personally disqualified lawyer is screened.
 In situations where the personally disqualified lawyer was substantially involved in a matter, or had substantial material information, the new firm will generally only be allowed to handle the matter if the former client of the personally disqualified lawyer or of the law firm consents and the firm reasonably believes that the representation will not be adversely affected, all as required by Rule 1.7. This differs from the provisions of Rule 1.11, in that Rule 1.11(a) permits a firm to handle a matter against a government agency, without the consent of the agency, with respect to which one of its associated lawyers was personally and substantially involved for that agency, provided that the procedures of Rule 1.11(a)(1) and (2) are followed. Likewise, Rule 1.11(b) permits a firm to handle a matter against a government agency, without the consent of the agency, with respect to which one of its associated lawyers had substantial material information even if that lawyer was not personally and substantially involved for that agency, provided that the lawyer is screened and not apportioned any part of the fee.
 The former client is entitled to review of the screening procedures if the former client believes that the procedures will not be or have not been effective. If the matter involves litigation, the court before which the litigation is pending would be able to decide motions to disqualify or to enter appropriate orders relating to the screening, taking cognizance of whether the former client is seeking the disqualification of the firm upon a reasonable basis or without a reasonable basis for tactical advantage or otherwise. If the matter does not involve litigation, the former client can seek judicial review of the screening procedures from a trial court.
Corresponding Former Massachusetts Rule. See DR 5-105(D) for last two sentences in (a); (b)-(e) no counterpart.