Rule 1.9 Duties to Former Clients

This rule says a lawyer cannot turn around and work against someone they used to represent, at least not on the same matter or one that's closely connected to it. If a lawyer represented you in the past, that lawyer cannot later take a case against you on that same issue or something related to it, unless you clearly agree to it in writing.

The rule also covers situations where a lawyer switches law firms. If a lawyer's old firm represented someone, the lawyer cannot later work against that person on the same or a related matter if the lawyer picked up private information about them while at the old firm. Again, this can only happen if the former client agrees in writing.

Finally, lawyers cannot use private information they learned from representing a client to hurt that client later, even after the case is over. They also cannot share that private information with others, unless the rules specifically allow it or the information is already widely known to the public.

This rule exists to protect people who trust their lawyer with private details about their lives, business, or legal problems. It means that trust does not disappear just because the case ends. You should be able to speak openly with your lawyer knowing they cannot later use what they learned against you, and cannot casually switch sides on the same fight.