(a) A partnership or employment agreement that restricts the rights of a lawyer to practice after termination of the relationship, except an agreement concerning benefits upon retirement; or
(b) An agreement in which a restriction on the lawyer’s right to practice is part of the settlement of a controversy between parties.
 An agreement restricting the right of partners
or associates to practice after leaving a firm not only limits their
professional autonomy but also limits the freedom of clients to choose
a lawyer. Paragraph (a) prohibits such agreements except for restrictions
incident to provisions concerning retirement benefits for service with
 Paragraph (b) prohibits a lawyer from agreeing not to represent other persons in connection with settling a claim on behalf of a client.