The Florida Bar




A lawyer who has formerly represented a client in a matter must not afterwards:

(a) represent another person in the same or a substantially related matter in which that person’s interests are materially adverse to the interests of the former client unless the former client gives informed consent;

(b) use information relating to the representation to the disadvantage of the former client except as these rules would permit or require with respect to a client or when the information has become generally known; or

(c) reveal information relating to the representation except as these rules would permit or require with respect to a client.


After termination of a client-lawyer relationship, a lawyer may not represent another client except in conformity with this rule. The principles in rule 4-1.7 determine whether the interests of the present and former client are adverse. Thus, a lawyer could not properly seek to rescind on behalf of a new client a contract drafted on behalf of the former client. So also a lawyer who has prosecuted an accused person could not properly represent the accused in a subsequent civil action against the government concerning the same transaction.

The scope of a "matter" for purposes of rule 4-1.9(a) may depend on the facts of a particular situation or transaction. The lawyer’s involvement in a matter can also be a question of degree. When a lawyer has been directly involved in a specific transaction, subsequent representation of other clients with materially adverse interests clearly is prohibited. On the other hand, a lawyer who recurrently handled a type of problem for a former client is not precluded from later representing another client in a wholly distinct problem of that type even though the subsequent representation involves a position adverse to the prior client. Similar considerations can apply to the reassignment of military lawyers between defense and prosecution functions within the same military jurisdiction. The underlying question is whether the lawyer was so involved in the matter that the subsequent representation can be justly regarded as a changing of sides in the matter in question.

Matters are "substantially related" for purposes of this rule if they involve the same transaction or legal dispute, or if the current matter would involve the lawyer attacking work that the lawyer performed for the former client. For example, a lawyer who has previously represented a client in securing environmental permits to build a shopping center would be precluded from representing neighbors seeking to oppose rezoning of the property on the basis of environmental considerations; however, the lawyer would not be precluded, on the grounds of substantial relationship, from defending a tenant of the completed shopping center in resisting eviction for nonpayment of rent.

Lawyers owe confidentiality obligations to former clients, and thus information acquired by the lawyer in the course of representing a client may not subsequently be used by the lawyer to the disadvantage of the client without the former client's consent. However, the fact that a lawyer has once served a client does not preclude the lawyer from using generally known information about that client when later representing another client. Information that has been widely disseminated by the media to the public, or that typically would be obtained by any reasonably prudent lawyer who had never represented the former client, should be considered generally known and ordinarily will not be disqualifying. The essential question is whether, but for having represented the former client, the lawyer would know or discover the information.

Information acquired in a prior representation may have been rendered obsolete by the passage of time. In the case of an organizational client, general knowledge of the client's policies and practices ordinarily will not preclude a subsequent representation; on the other hand, knowledge of specific facts gained in a prior representation that are relevant to the matter in question ordinarily will preclude such a representation. A former client is not required to reveal the confidential information learned by the lawyer in order to establish a substantial risk that the lawyer has confidential information to use in the subsequent matter. A conclusion about the possession of such information may be based on the nature of the services the lawyer provided the former client and information that would in ordinary practice be learned by a lawyer providing such services.

The provisions of this rule are for the protection of clients and can be waived if the former client gives informed consent. See terminology.

With regard to an opposing party’s raising a question of conflict of interest, see comment to rule 4-1.7. With regard to disqualification of a firm with which a lawyer is associated, see rule 4-1.10.

[Revised: 06/01/2014]