Rule 1.17: – American Bar Association

Model Rule 1.17 Sale of Law Practice Sale Of Law Practice A lawyer or a law firm may sell or purchase a law practice, or an area of practice, including good will, if the following conditions are satisfied: (a) The seller ceases to engage in the private practice of law , or in the area of practice that has been sold, [in the geographic area] [in the jurisdiction] (a jurisdiction may elect …

https://www.americanbar.org/groups/professional_responsibility/policy/ethics_2000_commission/e2k_rule117/