Breach of duty – this term refers to the failure to perform something which is required by the law to be performed. A similar term is “breach of contract”, which details the actual failure to do what one promised to do under a concluded by them contract. Proving a breach of contract is a prerequisite of any suit for damages based on the contract. The breach of contract should be claimed (pretended) by the right party – usually in the form of notary invitation to be served to the other party.