The American Bar Association’s Model Rule 5.6 says a lawyer may not offer or make an agreement “that restricts the right of a lawyer to practice after termination of the relationship.” The official comment explains why. Such an agreement “not only limits their professional autonomy but also limits the freedom of clients to choose a lawyer.” Massachusetts uses the same wording in its own rules.
On December 4, 2019, the ABA’s Formal Opinion 489 said it in four words: “Clients are not property.” When a lawyer moves to another firm, both the lawyer and the old firm may tell the clients. Then the clients decide. They can stay with the firm, follow the lawyer, or go elsewhere.