Technically, breaking a contract is not illegal. But a broken contract is evidence that can be used to sue someone for a crime. If our contract was "you pay me

Technically, breaking a contract is not illegal. But a broken contract is evidence that can be used to sue someone for a crime. If our contract was "you pay me $50 every month for a year and I give you service in return", and you don't pay me, I can sue you for fraud and use the contract as evidence. But if our contract was "you must say 'Hail, Emperor!' every time you see me", and you break that contract, there is no law that enforces that.