Sometimes the ability of natural or artificial persons to perform contracts or to enforce contracts against them is limited. For example, very young children cannot be held to bargains they have made, assuming they do not have the maturity to understand what they are doing; Misguided employees or directors may be prevented from entering into contracts for their business because they have acted ultra vires (beyond their authority). Another example could be that of people with mental disabilities, either by disability or by drunkenness. [39] Not all agreements are necessarily contractual, as it must generally be assumed that the parties intend to be legally bound. A so-called gentlemen`s agreement is an agreement that is not legally enforceable and is supposed to be “only honorably binding.” [6] [7] [8] Legal systems differ in their principles of freedom of contract. In common law jurisdictions such as England and the United States, a high degree of freedom is the norm. For example, it was established in American law in the hurley case of 1901. Eddingfield that a doctor was allowed to refuse treatment to a patient, although there was no other medical help available and the subsequent death of the patient. [149] This contrasts with civil law, which generally applies certain general principles to disputes arising from contracts, as in the French Civil Code. Other legal systems such as Islamic law, socialist legal systems and customary law have their own variations.
In certain circumstances, an implied contract may be established.