(a) Except as law may otherwise expressly permit, a lawyer who has formerly served as a public officer or employee of the government:
(1) is subject to Rule 1.9(c); and
(2) shall not otherwise represent a client in connection with a matter in which the lawyer participated personally and substantially as a public officer or employee, unless the appropriate government agency gives its informed consent, confirmed in writing, to the representation.
(b) When a lawyer is disqualified from representation under paragraph (a), no lawyer in a firm with which that lawyer is associated may knowingly undertake or continue representation in such a matter unless:
(1) the disqualified lawyer is timely screened from any participation in the matter and is appo