The distinctions between an action for a tort and one upon contract are such that where the one will lie the other generally will not; but there are nevertheless some cases in which either may be brought at the election of the party injured. Thus, it is sometimes the case, that, in a business relation, the law makes it the duty of a party to observe a certain course of conduct with regard to the rights of others, where by contract he has also undertaken for the same thing; and in such a case a breach of duty is coincident with a breach of the contract, and the party damnified has his election to sue either for the tort or upon the contract.
Cooley, Thomas M. "Of the Right to Waive a Tort and Sue in Assumpsit." Bench & B. 2 (1871): 218-26.