A judgment in a lawsuit is typically only binding on the parties to the lawsuit. Such a judgment is called a judgment in personam or inter partes. There is, however, another kind of judgment which is not only binding on the parties to the lawsuit but is also binding on the world at large. The lawsuit commences as a dispute between the parties but its subject matter is the determination of the status of a particular legal entity or physical thing. Such a judgment is called a judgment in rem, “a judgment about the thing.” An example of a judgment about the status of a legal entity is a court ruling that a union local is the bargaining agent for employees with respect to negotiations with an employer. An example of a judgment about the status of a physical thing is a ruling that a road over private property is a right of way. Declarations of paternity or maternity are also judgments in rem. Such rulings are conclusive against all persons. The relitigation of the status of the thing or person is prohibited for all time.
Some courts have held that notice to interested persons, not involved in the lawsuit, is not required. However, other courts have held that, when the judgment will be adjudicating on the status of land, all persons allegedly having an interest in the land must be made aware of the lawsuit. In Ontario, the Court of Appeal has specifically held that a judgment in rem will not be allowed to stand when residential property owners are not afforded an opportunity to be heard on the issue of whether their road is a prescriptive right of way, that is, a right of way because of its use for over 20 years. Notice to interested persons is often accomplished by public advertising of the lawsuit.
Determining whether a decision is a judgment in rem is sometimes difficult. One test is that, if there is no appeal review of the lower court’s decision, it may not be binding on non-parties.