A mass tort is a civil lawsuit that involves hundreds or thousands of plaintiffs and one or a few defendants in which the plaintiffs have the same or similar claims against the defendant or defendants. Mass tort lawsuits are often filed as class action lawsuits (a procedural mechanism for joining the plaintiffs in one lawsuit), and are typically based on alleged wrongful acts (torts) such as exposure of the plaintiffs to harmful substances (asbestos or benzene), or defective products (pharmaceuticals or medical devices), or invasions of privacy (data breaches).

In Ohio, mass tort litigation is a legal process that allows numerous plaintiffs who have been similarly harmed by a defendant's actions to bring their cases together in a single lawsuit. This type of lawsuit is particularly common in cases involving exposure to harmful substances, defective products, or large-scale invasions of privacy, such as data breaches. While mass torts can be filed as class action lawsuits, they are distinct in that each plaintiff may have unique damages and the cases are often more complex. Ohio follows both state statutes and federal laws governing these types of lawsuits. The Ohio Rules of Civil Procedure provide the framework for class actions, which require certification by the court that the case meets certain criteria, such as a large number of plaintiffs and common questions of law or fact. Federal laws, such as the Class Action Fairness Act (CAFA), may also apply, particularly when the lawsuit involves plaintiffs or defendants from multiple states. An attorney specializing in mass torts or class actions can provide specific guidance on the intricacies of these cases in Ohio.