She received confidential information about the case of Patient v. Doctor . She has now joined the law firm of XYZ, which represents the defendant Doctor in the same lawsuit. If Alice is an attorney, XYZ is not disqualified, provided the firm builds a Chinese wall around her. If Alice was a law clerk and is now an attorney, XYZ is disqualified. You represent Client, a telemarketer.
Client cheats some people, including Gullible, out of thousands of dollars.
Gullible accuses you and Client of fraud, and sends a letter telling all about the deception to the local paper which the paper publishes. You knew nothing about the fraudulent scheme. As soon as you read about the accusations against you, you send Gullible copies of letters between you and Client in which you advised Client not to undertake such schemes. No lawsuit, either civil or criminal, has been filed against either you or Client. Yes, because your action violates the duty of confidentiality.