Jus ad rem is a Latin

Latin

Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

 term of the civil law

Civil law (legal system)

Civil law is a legal system inspired by Roman law and whose primary feature is that laws are codified into collections, as compared to common law systems that gives great precedential weight to common law on the principle that it is unfair to treat similar facts differently on different...

, meaning "a right to a thing:" that is, a right exercisable by one person over a particular article of property in virtue of a contract or obligation incurred by another person in respect to it and which is enforceable only against or through such other person. It is thus distinguished from jus in re which is a complete and absolute dominion over a thing available against all persons.

The disposition of contemporary civil law jurists is to use the term jus ad rem as descriptive of a right without possession, and jus in re as descriptive of a right accompanied by possession. Or, in a somewhat wider sense, the former denotes an inchoate or incomplete right to a thing; the latter, a complete and perfect right to a thing. See The Carlos F. Roses, 177 U.S. 655; The Young Mechanic, 30 Fed. Cas. 873.

In canon law. A right to a thing. An inchoate and imperfect right, such as is gained by nomination and institution; as distinguished from jus in re, or complete and full right, such as is acquired by corporal possession. 2 Bl. Comm. 312.