Hello Eberhard,
ccTLD Managers do not have contracts (but for 5 or so).
I could imagine a bit of a combination of contract and policy. For example the ccNSO can recommend polices on behalf of ccTLDs, which once approved by the ICANN Board become ICANN policies. The contracts would be able to specifically reference the policies, and include penalties etc if the policies are not complied with. While not all ccTLDs have contracts – they should be able to benefit from the requirements that ICANN follow the approved policies. ccTLDs that are not contracted parties still have access to the other accountability mechanisms such as reconsideration and independent review that are in the bylaws should ICANN not follow a policy. Regards, Bruce Tonkin