Connecticut Rules of Professional Conduct (Connecticut Practice Book) 1.9: Duties to former clients: no adverse representation in substantially related matters and no misuse of their information

What does 1.9 require?

Having acted for a client in a matter, a lawyer may not later act for someone else in that matter or a substantially related one where that person's interests are materially adverse to the former client, unless the former client consents in writing after full information; the same bar applies to matters a former firm handled where the lawyer picked up material protected information. Information from the earlier representation may not be turned against the former client, except as the rules allow or once it has become generally known, and may not be revealed except as the rules allow.