Civil procedure: Jurisdiction: Personal jurisdiction: In personam + In rem + quasi in rem

In personam is a Latin phrase meaning "against a particular person". In a lawsuit in which the case is against a specific individual, that person must be served with a summons and complaint (E&W known as Particulars of Claim (CPR 1999) to give the court jurisdiction to try the case, and the judgment applies to that person and is called an "in personam judgment".

In personam is distinguished from in rem, which applies to property or "all the world" instead of a specific person. This technical distinction is important to determine where to file a lawsuit and how to serve a defendant. In personam means that a judgment can be enforceable against the person wherever he or she is. On the other hand, if the lawsuit is to determine title to property (in rem) then the action must be filed where the property exists and is only enforceable there.

In rem jurisdiction ("power about or against 'the thing'") is a legal term describing the power a court may exercise over property (either real or personal) or a "status" against a person over whom the court does not have in personam jurisdiction. Jurisdiction in rem assumes the property or status is the primary object of the action, rather than personal liabilities not necessarily associated with the property.

A quasi in rem legal action (Latin, "as if against a thing") is a legal action based on property rights of a person absent from the jurisdiction. In the American legal system the state can assert power over an individual simply based on the fact that this individual has property (bank account, debt, share of stock, land) in the state. Quasi in rem jurisdiction does not have much function in the United States any longer. However, in very specific cases, quasi in rem jurisdiction can still be effective.

A quasi in rem action is commonly used when jurisdiction over the defendant is unobtainable due to their absence from the state. Any judgment will affect only the property seized, as in personam jurisdiction is unobtainable.

Of note, in a quasi in rem case the court may lack personal jurisdiction over the defendant, but it has jurisdiction over the defendant's property. The property could be seized to obtain a claim against the defendant. A judgment based on quasi in rem jurisdiction generally affects rights to the property only between the persons involved and does not "bind the entire world" as does a judgment based on "jurisdiction in rem".