Harris v. Balk, 198 U.S. 215 (1905), was a United States Supreme Court case that exemplified the idiosyncratic types of jurisdiction state courts (and therefore plaintiffs) could assert through quasi in rem actions before International Shoe's (1945)[1] "minimum contacts" test replaced Pennoyer's (1878)[2] principles of "power and notice".

However, if a defendant, on whom in personam jurisdiction was unable to be asserted, owned property in the state in which plaintiff was situated, plaintiff could "attach" to the action whatever property defendant owned in that state.

Such an action was labeled quasi in rem and, when this occurred, state courts were permitted to assert jurisdiction over an out-of-state defendant on any matter, with the limitation that any remedy be limited to involving only the attached property.

As debt is considered actual property of the creditor, and, at the time was considered to be physically located with the debtor, when Harris entered Maryland, he brought along the debt he owed to Balk, allowing Epstein to attach it in a quasi in rem action and obtain jurisdiction over Balk.

The principles allowing the Maryland state court to assert jurisdiction in this case were subsequently overturned by the Supreme Court case in Shaffer v. Heitner (1977).