37 CFR § 11.109 - Duties to former clients.
---
identifier: "/us/cfr/t37/s11.109"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "37 CFR § 11.109 - Duties to former clients."
title_number: 37
title_name: "Patents, Trademarks, and Copyrights"
section_number: "11.109"
section_name: "Duties to former clients."
chapter_name: "UNITED STATES PATENT AND TRADEMARK OFFICE, DEPARTMENT OF COMMERCE"
subchapter_number: "A"
subchapter_name: "GENERAL"
part_number: "11"
part_name: "REPRESENTATION OF OTHERS BEFORE THE UNITED STATES PATENT AND TRADEMARK OFFICE"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "5 U.S.C. 500; 15 U.S.C. 1123; 35 U.S.C. 2(b)(2), 32, 41; Sec. 1, Pub. L. 113-227, 128 Stat. 2114."
regulatory_source: "69 FR 35452, June 24, 2004, unless otherwise noted."
cfr_part: "11"
---
# 11.109 Duties to former clients.
(a) A practitioner who has formerly represented a client in a matter shall not thereafter represent another person in the same or a substantially related matter in which that person's interests are materially adverse to the interests of the former client unless the former client gives informed consent, confirmed in writing.
(b) A practitioner shall not knowingly represent a person in the same or a substantially related matter in which a firm with which the practitioner formerly was associated had previously represented a client:
(1) Whose interests are materially adverse to that person; and
(2) About whom the practitioner had acquired information protected by §§ 11.106 and 11.109(c) that is material to the matter; unless the former client gives informed consent, confirmed in writing.
(c) A practitioner who has formerly represented a client in a matter or whose present or former firm has formerly represented a client in a matter shall not thereafter:
(1) Use information relating to the representation to the disadvantage of the former client except as the USPTO Rules of Professional Conduct would permit or require with respect to a client, or when the information has become generally known; or
(2) Reveal information relating to the representation except as the USPTO Rules of Professional Conduct would permit or require with respect to a client.