In Aldrich v. Aetna Company, 75 U.S. 491 (1869), the question was whether the mortgage of a vessel, properly recorded under an act of Congress, gave a better lien than an attachment issued under a state statute, and the decision by the state court was that it did not. The construction of the act of Congress and its force and effect as it respected the mortgage security under which defendants claimed a right or title paramount to that of the attachment creditor was necessarily directly involved, and a proper case for review existed.