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 Maryland, mass torts are civil actions that involve a large number of plaintiffs against one or a few defendants. These plaintiffs generally have similar legal issues or have been harmed in a similar manner by the defendant's actions. Mass torts in Maryland can be filed as class action lawsuits, which allows for the collective representation of the plaintiffs to streamline the legal process and address common issues in one court proceeding. These lawsuits often arise from instances such as exposure to hazardous substances like asbestos or benzene, defective products including pharmaceuticals or medical devices, or large-scale invasions of privacy such as data breaches. Maryland courts handle mass torts under the same principles as other civil litigation, but with special attention to the management of complex and numerous claims to ensure a fair and efficient resolution. The state follows both federal guidelines and its own procedural rules for class actions, which are outlined in the Maryland Rules of Civil Procedure.