Refers to one of three kinds of jurisdiction that federal and state courts assert, the others being in personam and quasi‐in rem. In rem jurisdiction was traditionally conceived of as extending to things (that is, physical objects or real property) located within the forum jurisdiction and was thus construed in the classic case of Pennoyer v. Neff (1877). However, as Massachusetts Chief Justice Oliver Wendell Holmes pointed out, all proceedings are really against persons. In rem jurisdiction differs from quasi‐in rem in that in the former, the res (Lat., “thing”) is thought of as being itself the object of the litigation, while in the latter, the res is merely attached to satisfy a potential judgment in litigation involving something other than the thing attached.
Assertion of in rem and quasi‐in rem jurisdiction in the twentieth century became complicated by the rise in importance of intangible property, such as trusts, as well as by the mobility of property, which presented baffling metaphysical problems of situs. Responding to this complexity, the Supreme Court in Shaffer v. Heitner (1977) held that assertion of in rem and quasi‐in rem jurisdiction must meet the same due process requirements as assertion of in personam jurisdiction under International Shoe Co. v. Washington (1945), which required that the defendant have minimum contacts with the forum jurisdiction (see Due Process, Procedural).
— William M. Wiecek
