American Bar Association Model Rules of Professional Conduct - Rule 1.18. Duties to Prospective Client
(a) A person who discusses with a lawyer the possibility of forming a client-lawyer relationship with respect to a matter is a prospective client.
(b) Even when no client-lawyer relationship ensues, a lawyer who has had discussions with a prospective client shall not use or reveal information learned in the consultation, except as Rule 1.9 would permit with respect to information of a former client.
(c) A lawyer subject to paragraph (b) shall not represent a client with interests materially adverse to those of a prospective client in the same or a substantially related matter if the lawyer received information from the prospective client that could be significantly harmful to that person in the matter, except as provided in paragraph (d). If a lawyer is disqualified from representation under this paragraph, no lawyer in a firm with which that lawyer is associated may knowingly undertake or continue representation in such a matter, except as provided in paragraph (d).
(d) When the lawyer has received disqualifying information as defined in paragraph (c), representation is permissible if:
(1) both the affected client and the prospective client have given informed consent, confirmed in writing, or:
(2) the lawyer who received the information took reasonable measures to avoid exposure to more disqualifying information than was reasonably necessary to determine whether to represent the prospective client; and
(i) the disqualified lawyer is timely screened from any participation in the matter and is apportioned no part of the fee therefrom; and
(ii) written notice is promptly given to the prospective client.