According to ISNICs bylaws they do have a dispute mechanism:
Article 31
A Board of Appeals handles disputes regarding the registration of domains. The Board of Appeals is autonomous and independent. ISNIC carries out decisions of the Board within 10 days after they have been passed or on the next business day thereafter, if the current registrant does not accept the verdict. ISNIC will not carry out the Board of Appeal's judgements if legal proceedings have been instigated in respect of the same issue or an injunction been placed on the use of the domain in question before the Board of Appeals has reached a decision. Cases involving the registration of domains or refusal to register domains may be referred to the Board of Appeals.
