Short answer “At arm’s-length” describes a relationship in which the parties act independently of each other. The opposite —“not at arm’s-length”— includes individuals who are related to each other by blood, marriage, adoption, and common law relationships. Not at arm’s-length also covers people acting together without separate interests, such as those with close business ties. Long answer The concept of arm’s-length is used, amongst other things, in registered charities to clarify private benefit. For example, promotional items must be supplied at arm’s-length at a reasonable market value and without any excessive private benefit to the supplier, the charity’s board, or any individual members of the board.