The particular provision for Registries - RA, Specification 7, Art. 2(a), for Registrars - via the Registry Registrar Agreement with the particular Registry, where each new gTLD Registry must include provisions for compliance with the relevant URS procedures and mechanisms (URS High Level Technical Requirements for Registries and Registrars, Art. 4, Art 5.).
The mechanism of such enforcement is simple and already existing - it is a complaint sent to the ICANN Compliance department.