Mass Tort Law or Class Action Law is an area of law in which one or a few people sue on behalf of an entire class of people claiming harm from a product or action. Mass tort cases can be challenging and very complex, often involve several expert witnesses, and require in-depth knowledge of information and laws.

Civil cases similar to tort lawsuits often involve identical facts and legal issues. The affected parties may join together to bring legal action against the party responsible for the tort. For example, this can involve using a manufacturer for a faulty product that has been responsible for several injuries and suing a big company accused of being responsible for a pattern of discriminatory action.

Here class-action refers to legal action undertaken by individuals (or a representative group) whose legal rights are similar because of their situation; comparable to the treatment of a group as "a single party." One group member acts as a representative party on behalf of all in a class action.

Here, in a class action, the representative party will represent only those they feel are the case members who will fully participate.

Here, representation usually is not automatic. The "class" are given time to respond to the actions done by the plaintiff and participate in the suit.

In a class action, the plaintiff and other class members can negotiate and continue to argue before the final decision.

People not part of the original suit may file separate charges or opt-out of the class action.

In class actions, individuals may join together on their behalf or behalf of other similarly-situated persons similarly situated to the defendant, described in similar ways.