Send a disengagement letter. In most practice areas, it is best to do this promptly at the conclusion of any representation. Doubt about whether a client-lawyer relationship still exists should be clarified by the lawyer, preferably in writing, so that the client will not mistakenly assume the lawyer is continuing to look after the client’s affairs.

No. Bob’s new matter does not involve Amy and none of her confidential information arising from the prior representation would be relevant to Bob’s new legal matter.

Assuming you learned financial information about Amy in the former representation that will be relevant in the divorce, you may not represent Bob absent Amy’s written informed consent.

Yes. In order to check future conflicts, a departing lawyer must take a list of clients and matters on which the departing lawyer worked. See Ariz. Ethics Op. 10-02.

Yes, you should consider clients of your former firm your former clients, for purposes of confidentiality and evaluating conflicts. However, the inquiry does not end there. Neither you nor your new firm are disqualified by ER 1.9 unless you were involved in the representation or otherwise acquired confidential information about the client represented by your former firm. Keep in mind that in a disqualification proceeding, it will be your burden to prove you were not involved in the client matter at your former firm and did not acquire client information.

Not if doing so disadvantages the former client, unless the information has become generally known. Information is not generally known simply because it is publicly available. This exception contemplates information widely recognized by members of the public in the geographic area or widely recognized in the former client’s industry, profession, or trade. See ABA Formal Op. 479.

Before you disclose the information, first you should contact the former client again, to discuss appeal of the court’s denial. See Comment 15 to ER 1.6, Ariz. Ethics Op. 00-11, and ABA Formal Op. 473.

No. You must protect a client’s interests in transitioning representation and should not taint successor counsel. Resolve any doubts about what to disclose to new counsel by confirming with the client. See AEAC EO-20-0001.

When representation of a joint client ends, that client becomes a former client, triggering ER 1.9 in terms of ongoing representation of the remaining clients. You can’t represent the remaining clients against the former clients unless all affected clients provide written informed consent. Most often, when a joint or common representation fails, the lawyer has to withdraw from representing all of the clients. See Comment 1 to ER 1.9 and Ariz. Ethics Op. 92-07.

Not without client consent. The duty of confidentiality survives the representation and there is no public records exception. See ABA Formal Op. 479.