Rule1.9. Dutiesto Former Clients.
(a) A lawyer who has formerly represented a client in amatter shall not thereafter represent another person in the same or asubstantially related matter in which that person's interests are materiallyadverse to the interests of the former client unless the former client givesinformed consent, confirmed in writing.
(b) A lawyer shall not knowingly represent a person inthe same or a substantially related matter in which a firm with which thelawyer formerly was associated had previously represented a client
(b)(1)whose interests are materially adverse to that person;and
(b)(2)about whom the lawyer had acquired informationprotected by Rules 1.6 and 1.9(c) that is material to the matter; unless theformer client gives informed consent, confirmed in writing.
(c) A lawyer who has formerly represented a client in amatter or whose present or former firm has formerly represented a client in amatter shall not thereafter:
(c)(1)use information relating to the representation to the disadvantage of theformer client except as these Rules would permit or require with respect to aclient, or when the information has become generally known; or
(c)(2)reveal information relating to the representationexcept as these Rules would permit or require with respect to a client.
 After termination of a client-lawyer relationship,a lawyer has certain continuing duties with respect to confidentiality andconflicts of interest and thus may not represent another client except inconformity with this Rule. Under this Rule, for example, a lawyer could notproperly seek to rescind on behalf of a new client a contract drafted on behalfof the former client. So also a lawyer who has prosecuted an accused personcould not properly represent the accused in a subsequent civil action againstthe government concerning the same transaction. Nor could a lawyer who hasrepresented multiple clients in a matter represent one of the clients againstthe others in the same or a substantially related matter after a dispute aroseamong the clients in that matter, unless all affected clients give informedconsent. See Comment . Current and former government lawyers must complywith this Rule to the extent required by Rule 1.11.
 The scope of a "matter" for purposes ofthis Rule depends on the facts of a particular situation or transaction. Thelawyer's involvement in a matter can also be a question of degree. When alawyer has been directly involved in a specific transaction, subsequent representationof other clients with materially adverse interests in that transaction clearlyis prohibited. On the other hand, a lawyer who recurrently handled a type ofproblem for a former client is not precluded from later representing anotherclient in a factually distinct problem of that type even though the subsequentrepresentation involves a position adverse to the prior client. Similarconsiderations can apply to the reassignment of military lawyers betweendefense and prosecution functions within the same military jurisdictions. Theunderlying question is whether the lawyer was so involved in the matter thatthe subsequent representation can be justly regarded as a changing of sides inthe matter in question.
 Matters are "substantially related" forpurposes of this Rule if they involve the same transaction or legal dispute orif there otherwise is a substantial risk that confidential factual informationas would normally have been obtained in the prior representation wouldmaterially advance the client's position in the subsequent matter. For example,a lawyer who has represented a businessperson and learned extensive privatefinancial information about that person may not then represent that person'sspouse in seeking a divorce. Similarly, a lawyer who has previously representeda client in securing environmental permits to build a shopping center would beprecluded from representing neighbors seeking to oppose rezoning of theproperty on the basis of environmental considerations; however, the lawyer wouldnot be precluded, on the grounds of substantial relationship, from defending atenant of the completed shopping center in resisting eviction for nonpayment ofrent. Information that has been disclosed to the public or to other partiesadverse to the former client ordinarily will not be disqualifying. Informationacquired in a prior representation may have been rendered obsolete by thepassage of time, a circumstance that may be relevant in determining whether tworepresentations are substantially related. In the case of an organizationalclient, general knowledge of the client?s policies and practices ordinarilywill not preclude a subsequent representation; on the other hand, knowledge ofspecific facts gained in a prior representation that are relevant to the matterin question ordinarily will preclude such a representation. A former client isnot required to reveal the confidential information learned by the lawyer inorder to establish a substantial risk that the lawyer has confidentialinformation to use in the subsequent matter. A conclusion about the possessionof such information may be based on the nature of the services the lawyerprovided the former client and information that would in ordinary practice belearned by a lawyer providing such services.
Lawyers Moving Between Firms
 When lawyers have been associated within a firm butthen end their association, the question of whether a lawyer should undertakerepresentation is more complicated. There are several competing considerations.First, the client previously represented by the former firm must be reasonablyassured that the principle of loyalty to the client is not compromised. Second,the rule should not be so broadly cast as to preclude other persons from havingreasonable choice of legal counsel. Third, the rule should not unreasonablyhamper lawyers from forming new associations and taking on new clients afterhaving left a previous association. In this connection, it should be recognizedthat today many lawyers practice in firms, that many lawyers to some degreelimit their practice to one field or another, and that many move from oneassociation to another several times in their careers. If the concept ofimputation were applied with unqualified rigor, the result would be radicalcurtailment of the opportunity of lawyers to move from one practice setting toanother and of the opportunity of clients to change counsel.
 Paragraph (b) operates to disqualify the lawyeronly when the lawyer involved has actual knowledge of information protected byRules 1.6 and 1.9(c). Thus, if a lawyer while with one firm acquired noknowledge or information relating to a particular client of the firm, and thatlawyer later joined another firm, neither the lawyer individually nor thesecond firm is disqualified from representing another client in the same or arelated matter even though the interests of the two clients conflict. See Rule1.10(b) for the restrictions on a firm once a lawyer has terminated associationwith the firm.
 Application of paragraph (b) depends on asituation's particular facts, aided by inferences, deductions or workingpresumptions that reasonably may be made about the way in which lawyers worktogether. A lawyer may have general access to files of all clients of a lawfirm and may regularly participate in discussions of their affairs; it shouldbe inferred that such a lawyer in fact is privy to all information about allthe firm's clients. In contrast, another lawyer may have access to the files ofonly a limited number of clients and participate in discussions of the affairsof no other clients; in the absence of information to the contrary, it shouldbe inferred that such a lawyer in fact is privy to information about theclients actually served but not those of other clients. In such an inquiry, theburden of proof should rest upon the firm whose disqualification is sought.
 Independent of the question of disqualification ofa firm, a lawyer changing professional association has a continuing duty topreserve confidentiality of information about a client formerly represented.See Rules 1.6 and 1.9(c).
 Paragraph (c) provides that information acquired bythe lawyer in the course of representing a client may not subsequently be usedor revealed by the lawyer to the disadvantage of the client. However, the factthat a lawyer has once served a client does not preclude the lawyer from usinggenerally known information about that client when later representing anotherclient.
 The provisions of this Rule are for the protectionof former clients and can be waived if the client gives informed consent, whichconsent must be confirmed in writing under paragraphs (a) and (b). See Rule1.0(f). With regard to the effectiveness of an advance waiver, see Comment to Rule 1.7. With regard to disqualification of a firm with which a lawyer isor was formerly associated, see Rule 1.10.
Effective November 1, 2017