A contract may exist to forbid the provider from disclosing the data to third parties, and it may be backed up by legislation that also aims to prevent the provider from acting unfairly. These approaches are difficult to scale up. If the cloud provider is very large, it will have subcontracting arrangements with other service providers, and they would have to be locked into the contract too. Also, the cloud provider may have numerous employees, and it may be very hard to vet them all to the standards wished by the data owner. Even cloud providers that have a huge reputation to protect, like Google, have had to sack employees for illegitimate access to customer data. It might become difficult for the owner to prove liability in the case of data breach, and even more difficult to take legal action and obtain compensation. Moreover, the international nature of cloud providers like Amazon and Google make it difficult to legislate their behaviour effectively.