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 Pennsylvania, a mass tort is a type of civil litigation that allows a large number of plaintiffs to sue one or a few defendants for similar claims of harm or injury. These cases often arise from exposure to harmful substances, defective products, or invasions of privacy such as data breaches. Pennsylvania courts handle mass torts through a coordinated process to manage the complex and voluminous nature of these cases. While mass torts can be filed as class actions, where plaintiffs with common legal issues are treated as a single class, not all mass torts are class actions. Each plaintiff in a mass tort may have individual claims and potential damages, which can be distinct from those of other plaintiffs. Pennsylvania follows both state procedural rules and federal laws, such as the Class Action Fairness Act (CAFA), which governs certain aspects of class action lawsuits, including those that may be considered mass torts. It's important for plaintiffs in mass tort cases to consult with an attorney experienced in this area of law to understand the specific legal requirements and procedures that apply in Pennsylvania.