Русско-англо-русский юридический словарь

If the obligor has a claim that is due against the obligee under the same legal relationship as that on which the obligation is based, he may, unless the obligation leads to a different conclusion, refuse the performance owed by him, until the performance owed to him is rendered (right of retention). (law.ed.ac.uk)

"contractual relationship. Legal relationship between contracting-parties evidenced by (1) an offer, (2) acceptance of the offer, and a (3) valid (legal and valuable) consideration. Existence of a contractual relationship, however, does not necessarily mean the contract is enforceable, that it is not void (see void contract), or not voidable (see voidable contract). ()

With regard to the four jurisdictional prerequisites, these are: "(1) there is an agreement in writing within the meaning of the Convention; (2) the agreement provides for arbitration in the territory of a signatory of the Convention; (3) the agreement arises out of a legal relationship, whether contractual or not, which is considered commercial; and (4) a party to the agreement is not an American citizen, or that the commercial relationship has some reasonable relation with one or more foreign states." Id. at 1295 n.7; see also Escobar, 805 F.3d at 1285. (Lexology)

obligation; duty. Broadly speaking, the words are synonymous in referring to what a person is required to do or refrain from doing—or for the performance or nonperformance of which the person is responsible. But there are connotative nuances. An obligation is normally an immediate requirement with a specific reference .

A duty may involve legal compulsion and immediacy, but the word carries an overlay of a moral or ethical imperative . More specifically, duty = (1) that which one is required to do or refrain from doing, esp. as occupant of some position, role, or office; or (2) any one of a complex of rights and standards of care imposed by a legal relationship. Sense 2 appears primarily in tort law, in which writers use duty only to mean that there could be liability. (Garner’s Dictionary of Legal Usage)