Legal Definitions - common-nucleus-of-operative-fact test

The common-nucleus-of-operative-fact test is a legal standard used by federal courts to determine whether they can hear state-law claims alongside federal-law claims within the same lawsuit. This test allows a federal court, which primarily has jurisdiction over cases involving federal law, to also resolve related claims based on state law if all the claims—both federal and state—stem from the same core events or circumstances. The primary goal of this test is to promote judicial efficiency and prevent parties from having to litigate closely related issues in separate federal and state courts.

Essentially, if the state and federal claims are so intertwined that they arise from the same set of facts, a federal court can choose to hear both, ensuring a more complete and efficient resolution of the dispute.

• Example 1: Civil Rights Violation and Personal Injury

  Scenario: A person files a lawsuit in federal court alleging that a city police officer used excessive force during an arrest, violating their federal civil rights. In the same incident, the person also suffered physical injuries, such as a broken arm and concussions, due to the officer's actions. While the excessive force claim is a federal matter, the claim for personal injury (like battery or negligence) is typically a state-law claim.

  Illustration: Under the common-nucleus-of-operative-fact test, the federal court would likely hear both the federal civil rights claim and the state-law personal injury claim. Both claims arise directly from the exact same "operative facts"—the specific incident involving the police officer and the resulting harm. It would be inefficient and unfair to make the plaintiff pursue the federal claim in federal court and then file a separate lawsuit in state court for the injuries stemming from the very same event.

• Example 2: Employment Discrimination and Breach of Contract

  Scenario: An employee sues their former employer in federal court, alleging discrimination based on a protected characteristic (e.g., age or gender), which is a violation of federal anti-discrimination laws. The employee also claims that the employer breached their employment contract by terminating them without proper notice or severance, which is a state-law contract claim.

  Illustration: The federal court would apply the common-nucleus-of-operative-fact test. If the alleged discriminatory termination and the alleged breach of contract both revolve around the same events leading to the employee's dismissal, then they share a "common nucleus of operative fact." The court would likely exercise its authority to hear both claims together, as they are intertwined by the circumstances of the employee's termination, saving time and resources for all parties and the courts.

• Example 3: Federal Securities Fraud and State Misrepresentation

  Scenario: A group of investors files a lawsuit in federal court against a financial firm, alleging that the firm engaged in fraudulent practices in violation of federal securities laws by misrepresenting the value of certain investments. In addition to the federal claims, the investors also claim that the firm's actions constitute common-law fraud and negligent misrepresentation under state law, causing them significant financial losses.

  Illustration: Here, the federal securities fraud claims and the state-law claims for fraud and misrepresentation all stem from the same series of deceptive statements and actions by the financial firm regarding the investments. These shared events form the "common nucleus of operative fact." The federal court would likely hear both sets of claims because they are so closely related, allowing for a comprehensive resolution of all disputes arising from the firm's alleged misconduct in a single proceeding.