Also known as: same transaction or occurrence · transaction or occurrence test · same-transaction-or-occurrence test · transactional test
Written by attorneys · grounded in primary & secondary sources — see below
A standard used to decide whether multiple claims share a common nucleus of operative fact. Claims satisfy the test when they arise from the same underlying events so that a plaintiff would ordinarily be expected to try them together in one proceeding.
Ortiz sued Summit Pipeline in federal court under a federal safety statute after a leak contaminated his fields. He added state claims for nuisance and trespass arising from the identical leak and resulting damage. The court determined that the federal and state claims satisfied the test because they rested on the same sequence of events and the same evidence about the leak and contamination.
The state charged a defendant with robbing six poker players during a single game. The defendant argued that each robbery required a separate trial. The court held that all counts met the test because they arose from one continuous episode involving the same participants, location, and sequence of events.
Select any source to read its text and confirm it supports the definition.
Investors sued a bank under U.S. securities law for misleading statements made in connection with foreign stock purchases. They sought to add state claims based on the same statements but arising from transactions executed entirely on foreign exchanges. The court found the state claims failed the test because the operative facts occurred abroad and lacked the required factual overlap with the domestic federal claim.
Employees signed employment contracts containing arbitration clauses that covered wage claims. They later argued that state-law claims for wrongful termination should proceed in court because they involved different facts from the wage disputes. The court applied the test and held that the claims arose from the same employment relationship and therefore had to be arbitrated together.
State-law claims qualify when they share a common nucleus of operative fact with the federal claim. This occurs when the claims arise from the same transaction or occurrence so that a plaintiff would ordinarily try them in one proceeding.
Supporting sources
No. The test is satisfied when the claims share a common factual core even if some additional facts support one claim but not the other. The key inquiry is whether the claims are so related that they form part of the same case or controversy.
Supporting sources
Yes. Even when claims arise from the same transaction or occurrence the court retains discretion to decline supplemental jurisdiction for reasons such as predominance of state issues or novel questions of state law.
Supporting sources
…of related claims in a single lawsuit. Rule 13 makes compulsory (upon pain of a bar) all counterclaims arising out of the same transaction or occurrence from which the plaintiff's claim arose. Rule 14 extends this compulsion to third-party defendants. Rule 18 permits very broad joinder of claims, counterclaims, cross-claims, and third-party…