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 New Hampshire (NH), mass torts are civil actions that can involve a large number of plaintiffs against one or several defendants. These plaintiffs usually have similar legal claims resulting from actions such as exposure to hazardous substances, defective products, or privacy violations. Mass torts in NH can be filed as class action lawsuits, which is a legal procedure that allows for many individuals to combine their similar lawsuits into one single action. This is particularly useful in cases where the number of affected individuals is so large that individual lawsuits would be impractical or inefficient. NH state statutes and federal laws govern the procedures and requirements for filing mass torts or class actions, including rules on how plaintiffs can join together, how a class is certified, and how notices are provided to potential class members. It's important to note that while mass torts can be filed as class actions, not all mass torts meet the criteria for class action certification, and they may proceed as individual lawsuits coordinated for pretrial proceedings.