45 CFR 1639.3: Prohibition.

Except as provided in §§ 1639.4 and 1639.5, recipients may not initiate legal representation, or participate in any other way in litigation, lobbying or rulemaking, involving an effort to reform a Federal or State welfare system. Prohibited activities include participation in:

(a) Litigation challenging laws or regulations enacted as part of an effort to reform a Federal or State welfare system.

(b) Rulemaking involving proposals that are being considered to implement an effort to reform a Federal or State welfare system.

(c) Lobbying before legislative or administrative bodies undertaken directly or through grassroots efforts involving pending or proposed legislation that is part of an effort to reform a Federal or State welfare system.