Kentucky had a law declaring unused traveler's checks to be abandoned property if they are not used after a period of fifteen years; such property escheated to the state. When the legislature reduced the period from fifteen to seven, the change was challenged as a violation of due process of law. The Sixth Circuit held that the legislation was consistent with the due process clause on the ground that substantive due process requires only that the legislation be rationally related to a legitimate government interest. In this case, the legislation shortening the period from fifteen years to seven was a legitimate revenue-raising measure. American Express Travel Related Services Co. v. Kentucky, 641 F.3d 685 (6th Cir. 2013). The court refused, however, to rule on the question of whether the law effected an unconstitutional taking of property without just compensation, unconstitutionally impaired American Express's contractual obligations, or was unconstitutionally retroactive in application.